....when they see 'would of' or 'should of' instead of 'would have' or 'should have', or am I in the advanced stages of pedantry?
No - you're perfectly normal for members of this group.
Unfortunately it seems to be becoming accepted usage.
I have to resist the urge to lean over and correct people who are typing it out in front of me. It's lazy writing for lazy thinkers.
Also currently getting annoyed at the astonishing quantity of greengrocers' apostrophes apparent in every missive from our Head at the moment. The constant irony of grammar in a Grammar School...