It's or its? Yes, I do know the difference

I'm a former copy editor (very former, as you can tell from my poor grammar, spelling, and general lack of interest in the English language). I even consider myself a "reformed" copy editor, insofar as I try not to correct people when they speak or write (mostly because I'd spend all day doing it, otherwise ... and also, I'm not immune to the same mistakes myself). Still, sometimes I appreciate being bashed for a stupid mistake. Like using "it's" when I should use "its." Easily avoidable, yet I did it myself just last night. I even caught the mistake but didn't correct it, figuring nobody would notice. Somebody did (Laurel). So I fixed it. Blah.