Trolling (in case you didn't know) is when someone purposely plays a bad opening when they are higher rated then their opponent.
A GOOD TIME TO TROLL
The only time you should be trolling someone is if you are playing your best friend. Period. Next.
WHY YOU SHOULDN'T TROLL
1. It insults your opponents chess skills.
2. It can backfire really badly! I was once playing a 1200 at bullet (I was around 1135-1140), and they underestimated my skill and played the Grob. This resulted in me winning the game, which was a big blow to their rating, and and also maybe their confidence.
P.S. I will see if I can find the game where someone trolled me.
Playing a "bad" opening is not trolling. Sometimes, practicing unorthodox or dubious openings can be good practice (or throw your opponent off). And in the case of bullet, almost any opening is viable.
da grob is good opening