I have to admit, it doesn't bother me much if I don't get greeted when I walk into a shop (guess it's the Britishness thing again :) ). It's nice, but I'm generally happy to quietly take some time to browse through myself and just ask for some help if I need it.
That said, if I do ask for help, then I would expect it to be gladly given. I went to my LQS recently looking for all the fabrics for a bargello quilt. It was the first time I'd really asked for assistance in the shop, and they were fantastic - after I'd picked out my first few fabrics, two of the employees helped to pick out more fabrics that would work well. Definitely a very enjoyable shopping trip (even if it did leave my purse a little lighter than I'd originally meant :D )