I only buy a bass if it's the one I'm actually buying. There are too many variables even if it is the same bass that you then buy online. I went back on this recently and learned the hard way, having to return something I played in store but purchased online.
Funnily enough, I'm strongly against buying used now for the same reason. Either I've been very unlucky but I have come across so many chancers trying to sell me something that clearly did not function properly. I would always play these basses first, in person, but spot the problem every time. I've had broken allen keys in saddles, neck bows bigger than a banana, frets which could slice your fingers, tuners that required an iron grip to turn and basses that weighed 3 lbs heavier than advertised. The seller is always upset when I point these problems out...