It's very easy to pick up some small but niche artist that is not on Bandcamp, and upload their music pretending to be them. (It's of course very illegal, but I personally know artists this has happened to).
It's harder to fake an entire label. Before you buy anything on Bandcamp, check that their label links to them, otherwise you could well be supporting a scammer.
Yes, quality control is something else where Bandcamp could drastically improve. New releases are riddled with questionable stuff. Blatantly copying an existing artist is one thing, but often it's popular stuff just slightly modified, usually pitched up/down with some new drum loop and then called a day. I know there's a whole artform in remixing/mashups/etc., but there's a line somewhere where it just becomes a lazy rip-off.
With a label account users clicking on the artist on a release page will go to the actual artist page which might contain releases from all kinds of labels.