Here are a few comments, for what they are worth. I am talking about this entire forum, and not just the "Instruments" section -----------
1. Some people take themselves too seriously.
2. When people are being insincere, it is often readily apparent. For instance, they may use humor when they feel a thread is somewhat silly.
3. The youthful beginners may not supply great ANSWERS, but they often pose very interesting QUESTIONS.
And "sincere" is not enough by itself. The person must have enough in common with you that some communication will take place. And, obviously, some people are sincere but just plain mistaken.
I personally feel I have learned very much reading and posting on this forum.