I'm really wanting this to focus on college or high school level education. Most of the debates on "bad teachers" discuss elementary and junior high - public education.
So - from your personal experiences (either yourself attending or something you know who attended and had problems) what *were* those problems
If that teacher failed a considerable number of students, seemed disconnected from the learning process or didn't make an effort to actually *teach* the class - what do you think should happen to him/her?
Bad professors usually fall into one of several categories (This can include pre-college teachers as well)
The Paycheck- This professor is there for his paycheck and no mistake. He often hands out A's like candy, spends seconds grading a four page paper, doesnt keep attendance, and comes across as terminally bored while lecturing. You as a student are an intrusion into his internet time and need to not bother him during class while you're doing your busy work. Count on him being late to class and probably early to leave, especially on Fridays.
The Control Freak- There's one in every school. This professor runs her class with an iron fist and woe betide the student who questions the divine right bestowed upon her. She often gives assignments with lists of instructions longer and more detailed than the project itself, takes a ruler to the margins of a paper (and fails it if the margins exceed her specifications by more than a few microns, hey, mistakes happen), and makes a gruesome display of any student foolish enough to question her.
The Preacher- The Preacher has an agenda and boy does he want you to know it. Be it religion, politics, grammar, or coffee, this professor has a preference and deity-given mission to spread the virtues of that preference to you. He may spend much of your paid-for class time going on at length about his chosen cause, reciting anything and everything he knows on the subject. This professor may grade students harder (or fail them entirely) who disagree openly with him and students who walk the sycophantic tightrope may find simply sneezing on a piece of paper constitutes A work. Antagonizing the Preacher is not recommended, he defends his cause with admirable gusto and he may discharge F's at those foolish enough to poke sticks into his cage
The Theorist- Her ideas are brilliant....on paper. The Theorist is harder to deal with than most because she truly means well and isnt trying to be malicious. She often prescribes odd and hitherto unknown methods of solving problems or composing work, insisting that she's found an amazingly simple new way of solving a problem. There is no room in the pedagogy for different learning styles, the Theorist is convinced her ways can overcome ANY obstacle. This may range from a mildly annoying quirk of an otherwise good professor to a textbook-rendingly frustrating mission.
The Uberfesser- You shouldn't argue with this professor, he wrote the book on the subject. No, really, he did, and you're using it in class. The Uberfesser knows more than you and he's happy to rub that fact in until you're ready to slit your wrists with a scantron out of frustration. With a degree comes an earth-shatteringly large portion of arrogance, mere students are there to bask in the Uberfesser's glory and wisdom, not ask questions. To him, ALL questions are stupid and there is no escaping just how WRONG you are.
The Hardass- She doesn't tolerate talking, chewing gum, eating, drinking, staring, sneezing, scratching, folding, writing, reading, twirling, or handling of any kind whatsoever. And dont even THINK about any sort of messing, tweaking, twiddling, blinking, breathing, or putting because you'll find yourself kicked out of class in no time FLAT, mister! The Hardass has issues and she wont stop until she makes them YOUR issues. Maybe she falls into the "those who cant do, teach" category, maybe she feels trapped, maybe she just went through a bitter divorce, maybe it's Wednesday, no one knows for sure. But walking into class is spinning the wheel as to what will send her into a tirade today. Oh and dont think so loud, you're distracting her.
The Dude- The Dude is, like, too cool for all this. He wants to be your friend, your pal, your buddy! Unfortunately, he doesn't want to teach, that's for squares. His classes are insanely easy and usually consist of chatting about some aspect of pop culture or whatever the kids are into these days. The Dude sheds the traditional trappings of boring school and likes to rock with catchy educational tunes and quotes from famous celebrities. Those looking for a bird course will be happy, but those of you wanting to learn something better start crackin' the textbook.
The Monopolizer- Other classes? You have no other classes. This professor assigns double digit hours of homework a night, after all how are you going to pass her class unless you review all material sixteen times? She may start class early ("to get enough time in") and run class VERY late ("to make sure we've covered everything") and be aghast at the suggestion she may need to scale back her workload. There are microwaves in the student lounge, a machine that dispenses burritos, a couch, and a bathroom all in the library. Why do you need to go home? She feels that school (in the form of her class and her class alone, of course) is the single most important priority in a student's life, I mean, getting hit by a bus is NO excuse not to finish your 20 page summary the night it was assigned.
The following professors are annoying, but these usually manifest as irritating behaviors in otherwise passable professors.
The Timebug- This professor runs on a clock, but no one has figured out whose. He may be three hours early or an hour and 45 minutes late, but he'll get there...eventually
The Writer- The Writer is well versed in his subject. So much so that he actually wrote the textbook for your class, you can pick it up in the student store...along with the supplemental test prep book, the homework study guide, the supplemental reading log, and the signed copy of his autobiography. Oh, all of those are mandatory for class.
The Librarian- Keeping chiropractors in business for decades, this professor cant be satisfied with one book so they say "**** it! Get 'em all!" This can be particularly grating when most of the "required" course materials are inevitably NOT used for anything.
The absolute worst professor I ever had was a welding professor. He was a top-notch welder, I'd have hired him to put metal together in a heartbeat but my gods the man couldn't teach a goldfish to eat it's own ****. If you picked the stuff up intuitively, you were golden. If you needed help however, then you were just being stubborn and not listening. He made no bones about the "I dont have to teach, I've got tons of money. I teach because I WANT to!" bit and never ceased reminding us of this.
He was sexist as hell and didnt really try to hide it. Our class had a single woman in it who pulled her weight like everyone else, did her work as good as (in some cases better than) anyone else in the class and the ONLY person who had a problem with a pair of C cups holding a stinger was the professor. The guy also stood up there in front of class and gave a 20 minute lecture as to why we should vote yes on Prop 8, a lecture I stood up in the middle of and walked out.
The most fun came when he nearly ****ing KILLED me, twice. The first time, he had a stinger (the bit that holds the welding rod) in his hand and he moved it past me. The tip of the rod came within about an inch of my nice hot, sweaty neck. For those of you playing along at home, I was wearing a leather welding coat with metal fasteners on it that were touching the work surface. If that rod had touched my neck, I'd have had 70 amps go through my heart, several orders of magnitude beyond what it would have taken to kill me.
The second time, he grabbed a LIT oxyacetylene torch out of my hand. He did this AFTER walking up behind me while I was wearing cutting goggles that eliminate any peripheral vision. I jumped a little bit and almost dropped the torch. Luckily it didn't cut any of the fuel lines (which would have ignited and killed everyone in the shop had the flame gone back to the fuel tanks).
The man was a grade A moron.