They stop innovating, supporting, and updating.
My Tungle.me syncing started having problems several months ago and I kept pushing off spending time trying to fix it because after I went through an initial round of trouble-shooting it still didn’t work and I was stumped. Today, I dug back into the issue and again fell short. So I wanted to email them, but couldn’t find an email address anywhere. I went to their Twitter account, but they haven’t updated since February. Lastly, I went to their blog and their last post was in May…right after they got acquired by RIM (Blackberry).