FWIW, the Schwinn MTB I'm currently working on seems like it has "some" quality to it. I has a mid bottom bracket and the cranks look decent. the rims are allay Araya.... So there's some quality to it. But yeah. Right now I'm debating on if I should buy a new derailleur for it or just turn it into a single speed by picking what gears I want and shortening the chain.
One of the wheels on the derailleur is sluggish and when you pedal backwards the chain binds some. I mean I know you don't need to pedal backwards and it's probably not a big deal but it's annoying. LOL. Plus I would think that gives some resistance when pedaling.....