I don't mind the easy to confuse phrases being misused. I'm not perfect myself. The thing that really bothers me is when people spell words phonetically without bothering to ever check if the word is wrong or not. Worse still is if they do it on purpose.
I'll give some real examples from a 22 year old woman I know. This is the way she uses words.
2 = to, too
n = and
i b = I'll be
sum = some
tuff = tough
wiff = with
gud = good
every1 = everyone
If she was writing me a quick text message on her phone, I wouldn't mind so much. But she'll type an entire email to me this way. That is just plain laziness.