It's sort of subjective, though. In what sense you regard straight as the default is an issue. For example, one could ask if they would act differently in some ways if they knew that there were gay people present. If you're saying things that would have you saying "sorry man, I didn't know you were gay", then you're doing straight as the default in a bad way. I think 1b especially, and in particular, how a straight person responds to being hit on by a same-sex person should roughly correspond to what they would find reasonable as a response to their unrequited attractions to anyone else. Well, that's the ideal anyway. The less OMGWTF whenever it does come up, the better.