Great topic.
I like to learn everything I can. If I'm simply doing research for general sample sizes from a chick I don't plan on doing much with, I interrogate her hard after sex. Add that to my data.
If she's a girl I like and want to date, I'm a bit more sneaky about it, since asking her too much, too quickly will put her on guard. She'll purposefully hide or construe information. One chick I quasi-dated told me she didn't drink much, because I asked about her party habits a bit too transparently. Next time she came over to cook me food, she brought beer and I was like, "I thought you didn't drink much?" She told me it was for me (but brought two). She drank only a little of hers, but I suspect it was to keep up the act. She went on vacation like a week later and told me that she drank a bunch, but added to it, "I don't usually drink, buttt." Girls are good at hiding or warping information. When she pushes for a relationship, I was interested, but my hesitations about her party habits and promiscuity kept me on the fence and she auto-rejected when I didn't outright ask her to be my girlfriend.
As for relationships, she told me how her first serious boyfriend had cheated on her. She blew it off and hoped that at least it wasn't an affair, but as long as he just fucked her, it was okay. This told me that I'd need to be quite the cheater to match this guy's level of fuckery with her, if I did date her seriously. Then, that guy left her for the chick he had an affair with. This destroyed her. Then, like 6 months later, he came back when it didn't work out with the girl. She accepted him and they dated for a while, but then she ended it (probably because she lost respect for him coming back to her). You can see how all that would affect dating her. She's going to prefer a very particular type of relationship dynamic (hot/cold, some side bitches, etc). I could do the side-bitches thing, but I'm not going to be chase-y when I do something wrong (something she obviously digs, from all her other stories).
There isn't a statute of limitations on previous behaviors or previous relationships. You have to gauge the degree to which the past behavior affected her and if you can overcome it. it's extreme to say, but if a guy in her past was exceptionally shitty to her (and she stayed with him), you have a hard hill to climb if you want to maintain her respect. If you find out her ex had her in a sub-dom relationship, had her drinking his cum off the ground with a slurpy straw, and that she let him ravage her asshole on demand, and YOU'RE not doing that, you need to be doing it. Fast. Otherwise, she will see you as less dominant than him.
I'm not saying this needs to be done 100%, but the more you do it, the more you can be confident she respects you. Guys want to say stuff like "Don't worry about your competition; just be manly and she'll like you," but the emotion of jealousy, while negative in its own rights, DOES point you towards truth. If you're feeling jealous or inadequate about an ex-boyfriend, there's a chance she feels the same way. The trick is taking that emotion and using it to better yourself, and, at the same time, not letting her see that you're jealous.
It's a tough balance. Such is relationships.
Let go of the emotional pain, but not the information. Forget nothing she says. Ever. You might find that the years down the road, she says something and it conflicts with something she told you three years prior. And that contradiction could change everything you know about your girlfriend.
How much can you tolerate? Well, no girl is perfect. You'll only be a One-Night-Cowboy if you let the smallest blemishes keep you from dating women. There's nothing wrong with it, especially if you don't WANT a relationship, but if you do, your obsession with perfection could turn to paranoia. I say this from personal experience and it's something I still occasionally deal with (my relationship standards are ridiculously high).
Hector
