Yeah, back in the day my brother had a 96 GMC Jimmy that we brought to a Firestone lube place. They sprayed belt dressing all over the belt and it went all over the hood as a disgusting black crud and when we went to pick it up it squealed like a pig, and their "courtesy check" section said "Needs new belt". The belt hadn't squeaked at all before then and there were no signs of cracks or missing ribs. It seems that all too often places try to go above and beyond and thats where they can screw up too. We've had better luck with other quick lube places, I've always checked the dipstick and filter before leaving those places to make sure everything is how it should be.
I do all of the fluid changes for my vehicles on my own now and have done most repairs and other maintenence(brake jobs, etc.) myself.