Take a quick look at the Community Support - Free Hosting forum.
See how many people have lost their sites and their work because of inactivity. Remember you have to log in to the Forums (not the cPanel) and stay for a while (couple of minutes, and you do not have to post) once every 14 days. If not, you get suspended. But you can unsuspend yourself anytime withing the following 10 days. That is 24 days! For a good free website, what could be easier? But some want everything for nothing.
Also see how many have been terminated for nulled scripts (warez, programs that you are supposed to pay for but you get it from a 'friend' or website for free). Even linking to places with nulled scripts will get you locked out and all your files deleted.
Using copyrighted material is another no-no. Making anything that looks like another site (Paypal, Wells Fargo) will get you busted for 'phishing' even though you were not trying to gather information.