You can still neg via text. But you are correct, you don't have the added luxury of being playful with non-verbals...
All that means, is when you do tease/dhv/cocky-funny/whatever.. It HAS to be solid, and well thought out. Instead of immediately responding to the first thing you think of, try taking a minute or two, and thinking.. what is the BEST most BADASS PUA thing i could possibly say. Most times i'll think of something kind of funny immediately, but honestly, if I think harder, i can find something better.
I'm guilty of not doing that too..
This is an example of when I did.
HB: Tell Me what color!
Me: What color what?!
HB: Hurry Chose like... French or....?
Me: I assume nails? French.
HB: French it is. My hair smells delicious right now!
Me: I beg to differ..
Me: I also changed my mind.. French isn't going to do it for me..
HB: Make up your mind!
Me: So bossy...
HB: You're weird
Me: we'd make a good match then, Too bad..
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you can be playful and cocky funny. but you have to make sure it's mild.. and make sure to utilize smileys!

:-/ :-p