Since English is/was my second language, i always get ticked off when I read some of the poor english perpetrated at us.
"Could of", "Would of", are just incorrect, not even bad english. It should be Could have (Could've, Would have, Would've is acceptable)
Sorry to be picky, but especially teen agers are beginning to utilize those phrases and it irks me to no end.
I'm still struggeling with english as my 1st language. :)