A "good lens" usually has a four-digit price tag, like $1299. Or $1399. Or $1799. Or maybe even $2499.
A "cheaper lens",as per your original question, has a lower price tag figure on it than a good lens has. So, if a lens has a three-digit price tag, say from $999 down to 100, it is by definition, a cheaper lens than a "good lens".
A bad lens is usually priced in the two-digit range. eBay is full of bad lenses priced at $10 to $90. Stuff like the Asanuma 28mm f/3.5 M42 mount for $19. A "bad lens" often comes with explanatory notes, like "slight cleaning marks", which might mean it's scratched up to beat he)). Other bad lens notes include, but are not limited to "slight de-cementing visible", "pock mark on rear element", "chipped rear element, coatings worn away", and the always great, "fungus visible", and the oldy-moldy favorite, "severe hazing visible inside."
The above post is meant half seriously,and half in jest. I've taken some good pictures with "cheaper lenses",and some with bad lenses too. And some with good lenses.