I know I'm not a native speaker, but I need to address this.
I keep seeing "could of" and "would of" and "should of" in subs. We all make mistakes when we write, but I feel there is a pattern. I think the person volunteering (we all make mistakes, I support every volunteer, except for the Evil Googlators) doesn't know the correct form, or I'm mistaken and it's now acceptable in Standard English.
It's one thing to make a mistake because we keep the structure of one language when we translate into another, because we might be tired or something, but isn't there a grammar rule for this?
Unfortunately, I can't point to a certain episode or sub, because it just caught my attention one too many times.
It doesn't seem like it's intentional, like the person portrayed is someone who would make this mistake as part of their characterization.