Sirtis is a bit snarky at times but I think some of it is just for laughs. Although she makes constant jokes about the other Star Trek shows, she's admitted in an interview with Star Trek.com that she thinks DS9 is the second best Trek series (behind TNG) and was the third best sci-fi show on the air in the 90s behind TNG and Babylon 5.
Yeah, she's a riot. A breath of fresh air in the notoriously stuffy environment of conventions. She don't take herself too seriously, and she's just happy to chitchat with people instead of lecturing them. Some fans have a dislike for her because she don't treat Star Trek as being "serious business". The same fan usually complain about "canon violations" and "disrespecting the franchise".