Ah, many of these irritate me from time to time. In casual conversation, most of my friends and associates, or even I(!), will use some variation listed here, just for effect. No problem there. And in a post in a forum such as this, the grammar and pronunciation isn't all that important to me. Occasionally, it can be confusing, and I hate it when I've included some typo that makes it appear that I don't know the correct word...and don't notice until it's too late to edit.
It is publications and news broadcasts that I wish would get it right!
The sports player did not miss a game because he has a groin. Everyone has a groin! He missed the game because he has a groin injury!
There is no such thing as stick-to-it-iveness. The word is tenacity! Good gravy!!
Gosh, those are just the first two that come to mind. If I think of more, I'll share.
Hugs and butterflies,
~T~