talking about hooking up for sex too soon.

When they admit that they are married. When they lie about their age by a couple of decades. When they tell offensive jokes. If they are looking for a partner who also has to be of their religious faith or willing to join it. Oh, and what @DrBill said.

One woman started telling me about her guns.

Sometimes it’s just a feeling that I have that tells me steer clear.

When they make any mention of how gorgeous they are. It is off putting, because I don’t believe them.

Like @jca it’s the vibe I get from them most of the time. A lot of times it’s because the person can’t hold a damn conversation these days. I get one word answers or they don’t answer all of my questions. They don’t perpetuate the conversation. This frustrates me to no end and I just say fuck it at that point.

I don’t have to worry about saying no. It’s usually the other person who does (or doesn’t) do that. I would never be interested in someone who wasn’t interesting, though. And that becomes apparent long before you could even say you were getting to the point where you would say no. You just don’t pursue something that isn’t interesting.

1. Too many pictures of themselves.
2. Too many pictures of their places of travel.
3. Picture/s of them standing next to one of their ex-signifigant others (even the partials of their ex).
4. Bragging about how they’re a great catch or how great they are (bigtime turnoff).
5. Overly religious, or women who are not tolerant of others religious/spiritual beliefs.
6. Women who lash out against all of the ‘losers’ they run into on/offline. (bigtime turnoff)
7. Women who are too traditional as far as gender roles go.

When I notice that there behaviour online is more confident and rude than I think it is in reality, makes me think that they just heve the courage to be this outgoing because they don’t have to fear a face-to-face reaction.
Extreme attention seeking online, too many posts, pictures….
When they speak to me online, but deny or don’t acknowledge it when they see me in person (of course it can be awkward to run into someone you only talk to online, but a simple ‘hi’ would solve it…)
...

When I was online dating I was instantly turned off by people who put no effort into their spelling and grammar.

This question seems to presume that you are breaking off because of something the other did, yet I’ve not pursued on-line interactions simply from lack of time. When I meet someone in person I’d like to spend hours on chit chat, and that doesn’t work as well with on-line interactions. On-line suggests the satisfaction of fulfilling needs immediately, but this isn’t actually true.