Questions like these have never crossed my mind. Don't think I would care about farting. Sudden vomiting would be a surprise for sure but it would not interfere with my respect for my therapist at all, I think... unless they were intoxicated in session or something. These things are not character flaws or poor behaviors and can be beyond control. I would imagine that a T would likely excuse him/herself and go to the bathroom if they felt it coming... at least that's what I would do.