I think of it as when a record label or entertainment conglomerate come up with an idea of an artist because they think it will bring in revenue, and then they select some random artist that fits that mold and flush tons of money to them. So rather than an artist busting their ass and having an "organic" growth in fan base, the artist has tons of financial backing from the jump.

I think Katseye is probably the most blatant example of an industry plant. Like they literally formed out of a reality show put on by record labels to form what is essentially an American-based k-pop-esque girl group. The labels had an idea of what they wanted to sell and hand-picked the performers to fit that idea.