Just gotta go stand on them. My crude logic that I've used since 1997 is to put them on the floor and assess by seeing how easy it is to balance a nose manual, then crouch down in ollie position and see if the concave puts pressure in any direction that pitches me off my center line, and then blindly position my rear foot on the tail and see where it puts for scooping and popping. That covers how I would skate it and how natural it would feel shifting my feet into all positions. Not super precise since the trucks aren't on it, but much easier than nerding out on dims, getting a deck, and realizing it doesn't skate how you'd think.