Hi Gracie!
I just did a google search for an article for reference & saw that some places didn't mention it as bad for the pans. However, I've always been told to use oil as opposed to cooking spray & the literature that came with our Emerilware explicitly said not to use cooking spray. I'm not sure why some places mention it and others don't. Maybe there's some sort of subtle differences in pans?
In any case, here are some links:
Ehow - How to care for Non-stick cookware All about nonstick cookwares..... 10 ways to ruin a nonstick pan (about.com)
I don't remember where I read about the tomato sauce ruining the finish. It's been a few years -- but it was something I came across when I was researching nonstick pans for my hubby for his Christmas present. We've had our Emerilware since 2005 & haven't had any problems with tomato sauce, though - so take that part for what it's worth. Maybe it has to do with rapidly heating it? IDK?