I think it's always good to remember that communicating on the Internet has its pitfalls. It's so easy to misconstrue was someone has or hasn't said, and when you add to that symptoms of depression or anxiety we are all prone to making assumptions that might not be true.
The forums aren't a "live chat" environment, and back-and-forth social threads like this are the exception rather than the norm, so I don't think the average person coming through here is conditioned to sign off after every post. Also, with the way the forums are moderated, your post may take up to 12 hours to appear anyway, so even if you have said you're signing off for the night in a thread, that may not be seen till the next day.
I have even seen situations where, in a particularly intense thread where someone is struggling, saying "goodbye" at the end of a post has led other members to assume the worst.
I've been managing the forums here for a couple of years now, and I can assure everyone that instances of someone posting with the intention of hurting another person are extremely rare. We have a zero tolerance policy for that sort of thing, and it's a very friendly, supportive environment here as a result.
Bearing this in mind, if you read a post and you're not clear on its meaning, reply to the person and ask. Don't assume that they're being nasty, because it's incredibly unlikely. That said, if you see something that is obviously disrespectful, then you can always report the post to us and we'll look into it.
Finally, our forums can be clunky at the best of times as well, I know a lot of you report that you have lost posts from time to time. Please let me know if this happens to you, I am collecting a log of all these incidents so we can try and get our web developers to work out why it is happening.
Carry on! :)