Ladies and Gents! Which personalities/character traits have you learned to avoid/be careful with when first meeting a dating prospect?

I'm not talking about things they've done in the past because you would just be meeting them. If you are the type to figure that out someone's past mistakes right away, please do tell.

Also, if it's not a complete deal breaker, and you're just careful around people who are a certain way, how can someone make you feel better about dating him/her.
Ladies and Gents! Which personalities/character traits have you learned to avoid/be careful with when first meeting a dating prospect?
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