You can tell that you've made a mistake when that cricket screeching in the background is the only noise that's heard after you tell her something you think is particularly sexy. When she doesn't know how to respond to your dirty talk or when she takes offense to what you say, do not respond aggressively or reciprocally. Don't get upset. Continue to soothe and state that you are just talking dirty for fun. However, it is best to switch your use of profanity to descriptions of how she's making you feel, what she feels like to you, etc. You can still use imagery artistically to create that erotic environment where she feels a little wild and free to talk back.
Revealing a fetish
Reveal too much too soon and you're in trouble. A second date is not the time to break out the toys, ropes and videos. Be sure of your safe reception. Revealing personal details too soon can ruin the potential of a developing relationship. Treat fetishes like a relationship topic. This kind of discovery does not occur until much later within the confines of a stable relationship.
She may ask, but unless you are certain she knows enough about you and about herself to support this kind of knowledge, you are risking to be ridiculed and meeting the end of a possible sexually experimental connection. If you have to tell her about your secret stash of homemade porn, break it to her gently and assure her you won't progress to that stage until she is ready and feels secure, if at all. The object is to make her feel respected and safe knowing you will understand her wishes to either experience your fetish with you or pass on it.