to check the bearings or brakes, put it up on a milk crate, wheels off the ground and giv'em a hard spin, they should spin freely at least a dozen revolutions or so, and should both be the same, if one slows fast you'll have to tear into it to see whats goin on, also you shouldnt hear any rubbing, gringing, humming ect.
to check for a bent frame i stand 'em on there assend and look for uniformity, look especially right where the frame begins to widen at the back of the bottom a-arm mount