Just did Frontier from DEN-PBI. The base fare was $3.70 each. Good enough seat ($45 each) and one bag checked ($30,) I had two us, last minute ticket, to PBI for $176 total. UA wants $79+ for their E+ seats, though I do get a free bag on UA with the MR PLT and day of check in E+ for free. But they and AA wanted more like $500+.

Dirty plane, even the FA looked into the forward restroom and just closed the door it was so filthy. Same with the carpets, so I decided to keep my shoes on. But, they were on time and arrived early (plane fell out of the sky just at the right time.) SO how bad can that be?

You get what you pay for. I don't think it's a ripoff or scam, just not a very good airline. But, now that the legacies are playing the revenue game, sometimes these guys look OK.