I can’t say that all were Thules, but every bike roof rack I’ve ever seen that attaches to the “drip rails” or the door jamb has scratched, abraded, dug into, dulled or otherwise damaged the vehicle’s paint. For what it’s worth, the same is true for the trunk-mount racks that attach to the edges of the body panels via L-shaped hooks. From what I’ve seen, the inherent minor movement of the attachment points rubbing against the paint is going to mar it to one degree or another.
Thanks for the response. I actually got my roof rack at a discount from Thule after their most expensive trunk rack was leaving marks from the rubber feet on my trunk (which I could remove). At the time, they never told me that roof racks cause the same (and even worse) issues, since the marks from the trunk rack (which only stays on the car for a matter of hours) came off pretty easily. When I discovered the damage to my roof after removing the rack for a long trip this fall, the Thule representative told me that (as you said), anything you put on your car will cause damage. He actually said that Thule had repeatecly discussed the issue and decided not to warn customers about it because if they told people the racks cause damage nobody would buy the racks! I hadn’t had issues with Thule racks causing damages to previous vehicles (the representative thought the fact that my car is black may have made it worse), but I certainly would not have purchased the roof rack had they disclosed the possibility of damage, and am now considering going to a hitch rack. The reason I posted is that besides being a very unhappy consumer, I happen to be a lawyer and wanted to find out if it’s a common problem, which it appears to be. Therefore, I’d still like to find out if other people agree with you (and are upset about the damage to their cars).