Guys who cum within seconds of me getting their cock out (or before that)
Generally it's OK, I know they haven't done it on purpose, and it's not the end of the world, depending on how they handle the situation.
Embarrassment or frustration is OK and it's something I can be more aware of next time we meet.
But zipping up and saying "right, that's me done, see ya" is a block or future avoid.