Chafa is a handy word that simply means of low quality. For example, La tela está muy chafa. The fabric looks cheap, crappy, not of high quality.
Note that chafa does not inflect for gender: una camisa chafa, un reloj chafa. As for number, I’ve heard both camisas chafa and camisas chafas.
For some reason I associate chafa with fayuca, the low-quality, often pirated products that are sold cheaply in tianguis, open-air markets. You don’t expect something chafa to last very long. It’s not made for durability. Although the word is usually applied to products, it could work for anything whose quality disappoints you: a genre of music, a personal relationship, whatever.
The diminutive chafita may soften your evaluation a bit: No se ve tan chafita, amigo. It doesn’t look so bad to me.