I've also noticed this occasionally; thanks for providing a specific example I hadn't seen so far. The Forum's search feature has improved since we launched, but I also use Google sometimes, and it seems like they should be able to index us well.
The tech team will look into what's going on (especially with regard to the "underline" character response, which I agree is strange).
Use this thread to post things that are awesome, but not awesome enough to be full posts. Consider giving your comment a brief title to improve readability.
(Here's the last Open Thread, for reference.)