Bulk propane storage containers (anything containing more than one pound of LP) are prohibited indoors by NFPA regulations as well as by law in several states. In states where it's not illegal, the NFPA regs would still prevent a store from getting insurance if they weren't followed.
Personally, I hate exchanging a known-good bottle for an unknown bottle, and we only do it when we don't have another choice readily at hand. Even then, I leave DW outside with the bottle while I go in to pay. She makes an excellent guard dog, since she's far meaner and more violent than I am. :)
