I have been to Jensens a few times and I have only bought one thing from them. The few times I went in to just browse everyone seemed polite except for a few people. One or two people asked me while I was browsing if I needed any help and if I did to just holler.
The only thing I bought from them was a stripped lower. While the BG was going they were more than happy to let me check out the stuff behind the counter. That was just my experience YMMV.