This is just something that has been bothering me ever since I got into cars. Just want to vent a bit and share some info.
First thing is first: Camber is not the devil.
When I put my adjustable camber bolts on the front of my car and requested alignment at -2° camber up front you could have sworn the guys at the shop (Kent Brown Toyota in this case) thought I was absolutely insane. "Are you sure?" Yes. "You're going to get a lot of tire wear." No, I'm not, just do it.
Look... a little camber never hurt anyone. Hell, even up to something like -3° is probably fine. As long as you're not going crazy with it - your tires will be OK... one on condition.
The rest of your alignment needs to be in spec - and most importantly: toe.
Toe is which direction your wheel is pointing when the car is "straight" - towards the inside or outside of your car. Pointing to the inside is toe "in" - the outside is toe "out." Any out of spec toe settings can destroy your tires in a relatively short period of time. This is ridiculously accelerated if you have some sort of "custom" camber setting.
Say you have -2° of camber and something like 1° of toe "in" (assuming spec is something like +/- .2°)... you will end up chewing up the inside of your tire pretty quick. Not in like a couple weeks or anything - but it will significantly shorten the life of your tires - especially along the inside edge - very uneven wear.
Your best friend in all of this is an alignment as close to factory specs as possible. Your tires will thank you. And if you're into any sort of performance or modification - don't be afraid of a little negative camber - no matter what the shop tells you.
If you want to know a bit more about alignment, check out this Tire Rack article.
Note: I'm not a mechanic. I just play one on the internet. I don't guarantee this info is accurate - so you should also research stuff on your own. Hopefully it's at least partially correct.