I know that, simply by the numbers, there must be a number of players out there who are having legitimate issues with what Blizzard is doing. It's very likely that someone could browse a website about WoW, unknowingly download a keylogger, and then get their account banned by Blizzard. And I know that, for whatever reason, it seems like Blizzard has made some mistakes lately, and probably banned some people who truly didn't deserve it.
But here's the controversial part: Have you noticed, like me, that a lot of the "banned" stories don't seem to hold water? Here's one who says he lost his druid-- after logging on during an account suspension. I have to think that if you got suspended before, you likely got banned for doing the same thing again. Then there's the "my friend got banned and he doesn't know why" argument, or the "I gave my account info to a guildie and then got banned" argument-- if someone else is playing on the account that got banned, guess what? They got you banned. I know, I know, they're swearing they didn't use any third party applications, but I hate to tell you: if your friend did cheat, wouldn't he also be willing to lie to you, too?
But my point is not to ridicule people who got banned, my point is to help people who were "legitimately" banned wrongly. Blizzard has put up an easy guide for anyone who's worried their account might get banned called "How to Stay in the Game." (For the record, UI mods won't get you banned) They've also posted a thread about where to go if you have been banned (contacting firstname.lastname@example.org with your info is a good place to start), and finally, tips to stay away from keyloggers and such.
I've never been banned (but then again, I've never bought gold, shared my account, or hacked or botted, either), so I don't have a firsthand look at Blizzard's process. But issues with Linux aside, from what I've seen Blizzard has done a pretty good job with their player bans. You won't hear that from the players who actually got banned (they'll probably be in the comments section of this one yelling at me), but I haven't heard a story I believe yet where someone got banned without doing anything suspicious at all.