Not hard to guess at all. If they're too busy to type, they're too busy to do the trash, bonus and anything else that's skippable.
I wouldn't assume they try to optimise their key pressing. No answer means you leave the others to decide for you. They might be shy. Notably when they have no clue about the bonus, then can't decide. I met people knowing a flashpoint pretty well, but were happily surprised by discovering a new boss they didn't see before. On my server I could also suspect they don't speak English good enough.