So.. this has been bugging me for quite a while, as I noticed a lot of forum users doing this.. Alright, so 'should of', 'could of', and 'would of' are grammatically incorrect. It's actually 'should have', 'could have', and 'would have', rather than the former. Words like 'should have' are slurred into 'should've', so I think that's why many misspell it.

This is really not a problem, but I'm just telling you this, in case you didn't know and you have been using 'of' your entire life.