Of poor quality; coarse or inferior — used to describe goods, materials, workmanship, etc.
この店で買った靴は粗悪で、履いてすぐに底が剥がれた。
The shoes I bought at this store were inferior; the sole came off soon after wearing them.
粗悪な材料を使ったため、家具の寿命が短くなった。
Because inferior materials were used, the furniture's lifespan became short.
粗悪な模造品には注意してください。本物とは作りが全然違います。
Be careful of poor-quality counterfeits. Their construction is totally different from the real thing.