I have had similar experiences. It is beyond annoying for someone to message me, so that we may practice their English (and perhaps my Spanish/French), and instead, devolve into assumptions about America(ns) based on whatever media they have seen, and then show no interest in improving their grammar. I'm happy to clarify or debunk perceptions but language learning is the goal.
I have nearly given up on interactions with males on italki.
I have had success with both of us talking about every day life and also choosing to watch/read something that we can both access in our own language, the other's language, and practice discussing it. Movies are usually fun. There's a lot of cultural context that helps with language learning.