While we've all seen examples of bad plastic surgery to the face, I'd say this is the exception rather than the rule. Like all negative press, bad facial plastic surgery always seems to zoom to the top of the supermarket tabloids. And always with the least flattering photos. Good plastic surgery doesn't sell taboids/magazines. Jacko is a fine example of overdoing it and getting more than his share of time in the tabloids as a result. Like anything, plastic surgery can be overdone. Hollywood isn't necessarily the best place to be using for a reference.
Seen lots and lots of plastic surgery shows. Once they get around to showing the results, they vary anywhere from "I can't see the difference, can you see the difference?" to "holy crap, that a HUGE improvement". I also understand from a local radio plastic surgery show (guest host is a local plastic surgeon) that obvious benefits in person rarely translate well to the computer screen, in particular facial plastic surgery and liposuction.
I've personally seen both very good and very bad results from Botox. In the case of the very good, it was a 64 year old man who, quite surprisingly, looked like he was in his late 40's. In the case of the very bad, this man was in his late 50's and ended up with a partially paralized face. His personal reason for getting it wasn't for looking more youthful, but rather to deal with an irritating twitch around his eye. (Think that's called Bell's palsy, but not sure.)
People are typically very cautious when they sign on for cosmetic surgery, at least the first time they do it. Nobody wants to look worse afterwords, and if they have a friend whose 'after' work impresses them, chances are they'll go to the same surgeon for similar work, rather than flip to a random page in the Yellow Pages. It's the old question of the devil you know vs. the devil you don't know. Bad work translates to bad reputation, bad reputation translates to lost revenue. And vice-versa. If anything, cosmetic surgery is on the rise, not the decline. Dr Jan Adams (Discovery Health Channel, Plastic Surgery Before & After) regularly quotes growth stats for cosmetic surgery.
Of course, YMMV and all that. Personally if I had some extra cash to burn, I wouldn't mind a little lipo on the abdomen and maybe a blepharoplasty (although admittedly the idea of having work done around the eyes ooks me out a bit).