don't worry about seeing them in public. You won't. Most likely, these guys are all tough behind their screens but weak in person.

Just curious: what site(s) were you using? I wonder if there is a way to report this kind of abusive behaviour on there.

Well, you know, you bought into it.
I guarantee there have been guys who have messaged you once politely who you haven't given the time of day.
Not that I am saying his behavior is proper, whatever that means, only that it is clearly effective---I am sure you have passed over innocuous guys, but this guy you replied to, and once you have a connection, that's half the battle. It didn't work on you, buy a guy like that is playing the numbers, and he's doing it because it works.
If men always ignored guys like that, they wouldn't be trained to "come on so strong."
Plenty of women respond to this, don't tell me they don't!

I don't think this dude ventures very far from his Mom's basement suite.

Did you read the OP?
"he said if he ever saw me in public he would spit in my face and called me a whore cunt that I had obviously had other interests beside him because I wasn't answering him"
That's fucking psychotic.

Maybe more importantly:
"I guarantee there have been guys who have messaged you once politely who you haven't given the time of day."
Just because somebody is 'polite' or 'nice' or sends only one message, it doesn't entitle them to the attention of anyone else.

Yup, I've been polite, they've gotten so mean, or keep badgering me for sex. Ewww! No means no!!! Guys can't handle rejection well at all. I've given up on meeting anyone decent. It's lonely, but better than giving the ones that pester you a chance. Been there, done that. If you can't treat me with respect, and are not looking for something serious, don't waste my time. Most men are selfish, sex crazed, and far too many lie, cheat, and abuse women. Not just my personal experience, look at the stats. It's bleak out there.

That's not how it went down at all actually so as far as your "that was his tactic" thoery goes.. it was quite the opposite. I initially liked the guy we were having a good conversation and then he became obsessive so I was up front with him saying he was coming on too strong. You're not understanding where I'm coming from I guess. Some people I don't respond to their message because they aren't physically attractive to me and I don't see anything wrong with that. I'm not going to date someone that I'm not physically attracted to and that's not a crime. I'm also not going to waste someone's time playing nice "hey, I'm having a great day how are you?" It's a waste of both of our time. I've messaged lots of guys who never responded to me because I guess they didn't like the way I look or they read my profile and we had nothing in common. Doesn't mean I'm all butthurt about it and flip out on them threatening them?

If I compliment a guy, and he coldly turns away from me, should I tell him that he needs to smile more? What about the guys that I message politely who won't give me the time of day? I respond to these situations by backing off. Should I behave differently, or should I continue to respect their wishes?

Some guys are trolls. Some are not. Make time for who you see fit and don't apologize to anyone. You're right not to create false hope with courtesy responses. Sadly, until our culture changes to value safety of women and men don't tie their sense of self to caustic ideas about entitlement to women, shit like this will keep happening.

Reactivate your profile, block the idiot, and set filters on your profile for message content and what you are looking for. There are good people out there and online dating is another way of finding them. Make plans with your girls or a counselor to vent about the occasional garbage interactions. It helps. :) Godspeed, OP!

May I suggest volunteering, you know, helping out somewhere. Or perhaps joining some clubs that focus on your interests. Or maybe just be more open and communicative when you're out doing the things you enjoy doing.
Trying to find a partner, or even casual friends, on the internet is a silly proposition to begin with. You're not going to make any real connections that way.
The real connection come from being out in society, engaged in activities you either enjoy, or that are productive on some levels. There you will meet people who share your interests.
On the net all you're going to do is meet desperate people who are so caught up in themselves they aren't out doing what they enjoy or participating in their society.