Spirit FAs probably have more reasons to have shorter fuses than most. They tend to get full planes and more than their share of inexperienced travelers, many of whom speak a different language and some of whom would be traveling by ground if it weren't for the fares. Usually the gate people have to be the heavies on enforcing the bag policy (also not a great thing), but FAs can get into the act if people are storing rucksacks and those are crowding out paid-for carry-ons. Thankfully I don't see this happening much.

The FAs also have to do everything on a for-sale basis with some people not understanding the system, and they appear to be under a lot of pressure to move people in and out fast because Spirit tries to get in that extra flight per aircraft per day. That timed-for-perfection bit is bound to run into various delays a lot, which snowball until the last flight often gets out late.

Bottom line is you have a greater chance of getting one who's having a bad day.