This really bugs the crap out of me. Historically in my dealings with writing when you strike through text it means it is something that was a mistake and therefore not to be included in your thought!

Editors use it to strike out something that isn't needed.

If you want to use it in posts then I'll ignore whatever you wrote because it isn't meant to be there. Why write something if you're going to cross it out? It's annoying and childish. And if you say "no offense" then type out an entire offensive statement and strike it through, it doesn't make it any less offensive. You simply never should have typed it out to begin with. If you need to point out that you don't mean any offense, then it's obvious your statement is going to be offensive, so just keep it to yourself! 

Just use the strike-through properly people!