This...is a familiar train of thought to me. I've changed my name--I used to be Greenhowse--but I think I've debated this with you before
I'm really bad with names, so name changes don't bother me. I forget all of your names equally.
and do not see Trixie as a hero at all. I don't think just because she was enterprising she fundamentally captured a moral spirit.
I see that now that you're back again, and with Season 4 on the rise, we may very well restart our moral debates =)
Basically, I reject the idea of Trixie being a braggart and a liar. I see her as an artist. Maybe it's for-profit, or maybe it's a free show, but in any case she's living what looks to be a pretty meager life in a mobile home filled with the tools of her trade, for the sake of her life's true calling (magic-trick cutie mark), and I find that admirable. I don't mind her over-the-top persona or her fiction, and I think she's allowed to take pleasure in playing the role.
Rarity, AJ and RD tried to wreck her show, for reasons that I think fit with their characters. And Trixie (despite being a mere trickster) shut them down and looked good doing it. Twilight got some undeserved splashback, but that was mostly Spike's fault, and Rarity/AJ/RD indirectly gave it to Twilight much worse than Trixie did.
Trixie was a jerk to Snips and Snails, that's undeniable. But they were bothering her at her home, well outside of performance hours. And at least she kept up the act, and didn't tell little kids that there is no Santa Claus.
Snips/Snails/Spike caused the main threat in the episode, not Trixie. And they did it because they believed in Santa Claus. But I can't fault Trixie for not telling the kids the truth. That (as well as supervision) is their parents job.
When the main threat appeared, Trixie dropped the act. When everypony ran, and Snips/Snails continued to put themselves in danger, she deliberately put herself back into danger, and tried to fight a battle she knew was unwinnable, as well as telling a truth which made her uncomfortable, when the easy thing to do would have been to keep on running. It's not a lot, and wasn't effective, but I think that pushed her into hero territory.
The only effective hero, Twilight, hesitated to save the day because of Rarity/AJ/RD's actions, not because of anything Trixie did. If anything, Twilight felt a kinship with Trixie (another magician in the land of dirt ponies), and was more interested in watching Trixie's show than anyone else was (not counting children). And when the time came for Rarity/AJ/RD to apologize to Twilight, the non-contributors basically called Twilight an idiot, and took another uncalled-for shot at Trixie. Now homeless, Trixie puts back on her show-persona and runs away, which is a fair response to the welcome she received in this town.
For those interested, the Don Bluth animated film "Bartok the Magnificent" (a pseudo-prequel to Anastasia) basically starts off with the exact same premise as this episode (it even has an Ursa), but it's flipped so that the performer is recognized as an unwilling hero.