Amazing. I think some of you love roleplaying really much. For I can't see no other reason why you stayed in those games you described (those who didn't say they left, or said they played only because they had no other party to play in).
I thought I had some cases of bad games, but I had no idea! I did Al's stories already, but I didn't know it's that frequent.
So please bear with me when you think my stories "suck", and aren't bad - they're merely the worst I had!
First thing was in 2e, somewhere in the FR, on an island made by the DM, where war raged. I played a CN grey elf wizard/thief (this being my first RPG character, if you don't count CRPG's). We also had a NG (I think) Dwarven Warpriest of some LN Eastern War Deity (which didn't really make sense in the FR at all).
At one point, we fought some giants in a city. The dwarf was very happy of course, getting all those nice bonuses against dwarves. Yet he didn't happen to deal a killing blow to one of the giants (but I did). Later into the session, the priest accomplished something (can't remember), which made the Priest (or maybe only the player, which had probably drank a little too much to be very reasonable) shout out "I AM A WAR GOD!" Of course, I (or rather my character, which was the cheerful sort of elf) had to reply to that. "Sure, you are a god alright. Isn't that blasphemy or something?" "Well, I'm no war god, but I'M THE CHOSEN OF A WAR GOD!" I couldn't help myself: "Yea, you're that great? I didn't see YOU fell a giant today".
To that, the cleric answered with hitting my character, but he only laughed on I countered now with a hold person - and he fumbled his save. I told him that he should start this ridiculous behavior, and shoved him over. After that, the character really hated mine - refused to heal me (and other party members had to use their healing potions on me), and one day he actially kicked me from behind when I was studying my spells (when I asked the player whether he didn't think that was an evil act, he replied that he intended to become lawful neutral anyway, nevermind that the act was even more chaotic than lawful.). If the campaign hadn't just stopped (due to players just not showing up), I'd probably killed him some day - or at least, tried to, for he really ruined the fun of that campaign.
The other was a 3e campaign, where the DM made weird judgement calls: A rogue to be able to escape without us getting a chance to attack him. No init roll was made - the DM said "He just lets himself fall back in the window and can't be found them. It doesn't matter that my Ranger had an arrow knocked and his bow trained on him.
Later, we were guarding a caravan. We were travelling somewhere, and a river blocked our way. We searched for a ford to cross it, and found it. It barely went to our knees. One of our wagons, including the horses, was washed away in the currents...
Then he seemed to prepare the story very little, and the battles not at all. We usually fought enemies that outnumbered us and were of (almost) equal level or even of higher level. In short, the EL was +4 on the "easier fights". And we won every one of them, without any problems. The enemies hadn't any tactics we could discern, and it was very clear that the DM was pulling punches as soon as we started to be in trouble. He even let most of the party go on a rampabe in Waterdeep without being slaugtered by the Watch (in short: He made it clear that the characters were more or less invincible).
Also, he usually had us do easy tasks, but complicated them overmuch: We had to reach a certain isle (which we saw in a dream), but we couldn't wind walk there, we had to go there by ship. Of course, there was no ship available (we actually had a trading guild of a very large city backing us), except in a village of halflings (did I mention that one character, who was insane hat a phobia of halflings?). On another occasion we needed a 10.000gp diamond, but suddenly there was not a single one to be had (in a metropolis), and we would have to wait at least a month. When we invaded one of the jewelers' guilds, it turned out that they didn't know of the location of the mines, and sent the requests (encoded with something that resembles a 128bit key) via a magical box.
I changed my character twice in that campaign - and not a single time due to character death: the first (CN Wood Elf Ranger) didn't fit into the party after it became clear that what started as a "free for all campaign" was in fact an all-evil campaign. The second (CE Fey'ri Rogue/Assassin, master of spionage) didn't fit into the campaign - he wasn't really cut out for combat, but a skillmonger, but I got no real chances to play him.
Lately, we also have no real fights. We do encounter enemies all right, but the combat is usually resolved with a "you manage to kill/capture/whatever the enemies, all write down 13 points of damage", despite we're now quite combat focused (everything else doesn't really make sense).
And even though the game is all-evil now and was probably intended that way (we have an insane CE gnome alienist who wants to build his own doomsday device, a CE elf lich cleric of kiaransalee who hates his own race, a wood elf psychic warrior who is psycho, and my LE aasimar blackguard of bane), he wouldn't let me go into any details on how I torture my victims, saying he wanted to maintain some standards (but I think he doesn't have the stomach for it ;-) so of course, to annoy him a little, I start to go into datail whenever I let my sadistic streak show up and count the time it takes him to cut me off)
But I have to say, that because all these DM errors (and this was his first campaign - and his last, as after the last session, the campaign will end and he won't make another), the story flaws, the railroading and occasional lack of story, it is enjoyable to play there, cause the players (and the DM) are decent guys, (and I set the focus on the character and playing him instead of the story.) It's not nearly as bad as the stuff you described me.