I've never had a problem in the Cellar. That's because, to be honest, I go in there for 30 seconds, or look in the window to see if they have anything I've never seen in the flesh before. I'd never bother trying anything out or (gasp) buying something, because of all I've heard about the staff. Oh, and the steely glare I get as I walk in.
On the other hand, Rockers is the same group, and they're nice and helpful, if a bit young and metal. They've found all sorts of bits for me, and tell me to go and take anything I want down from anywhere in the shop, and play with it as soon as I walk in.
There's another one of the same group, can't remember which, where I had a similar experience. First time I ever walk in:
"Can I help you?" (Said nicely)
"I've just come in to look at basses"
"They're all towards the back. Feel free to get anything you like down and play it"