I was gonna say three things- bearing edges (especially batter side), dents or cracks, and hardware in good shape. Other than that, have a sense of priorities (wood type, shell thickness, wrap vs stain, etc). You should also be familiar with mounting and stands comparability (eg, Pearl is different and proprietary, some Sonor are, etc). Definitely good to play first but I’ve bought lots of things online and been overall fine. (More for things like snares vs overall kits though.) Generally contemporary drums from any of the main companies are going to be of good quality and outside of recording, there diminishing returns above a certain point for maple kits. Of the big brands, I’m partial to Ludwig, followed by Gretsch. DW I think you’re paying for brand and endorser fanboy-ism. Yamaha is the gold standard overall - especially for recording (in my opinion) but only really at the higher end maple and hybrid. Tama also fine. I played Pearl for a little while and they are okay but the mounting/hardware and overall quality aren’t my cup of tea. If you want to go more niche I like Sonor, Noble & Cooley and C&C but all those are going to be expensive. Cruser, that is a sweet set. If I were buying a new kit that wasn’t a Yamaha any time soon, I’d be going straight for Ludwig classic maple. Great sounding kits and very nice finishes. G650 I’m happy to look at anything if you want a second set of eyes. Generally it sounds like you know enough to be plenty dangerous. And remember, as long as their structural integrity is good, most any drum can be tuned to sound great.