To get most of your answers i think its good to set time frame:
Lets say we are at first few dates / weeks of online dating. Or, in other scenario - girl that expresses that she wants friendship, before going into relationship (then the scope is months).
In short term hook-ups its obvious - you want to bomb her with positives only, as PUA`s would say.

First- I think many guys have seen it themselves - Once you show woman you are interested in your vulnerability - its taken as weakness. You can literally feel and see attraction going away. What are your experiences?
How do you respond to shit test aimed to show them?

Second- What do you define as weakness and vulnerability?
Question for women - Have you ever rejected a guy after he has told/shown you? If yes, what is the biggest deal-breaker?