Will a bicycle trailer damage my (steel) bicycle?
These hitches don't work very well. They don't grab tightly enough, so they can twist around the bar and bump in to the wheel. As they twist they will take off the paint. They also require a lot of turns to attach and remove.

I had two trailers with this kind of hitch, and 3 bikes to pull with. I bought this Burley flex connector for each trailer:



I used this kind of hitch:



It works pretty well, but on one bike it's slippery, so the quick release lever can turn a little even when tight. But not enough that it's going to make the wheel fall out. Also, on one bike it bumps in to the QR, so I have to put it in just the right spot.