Yes, Mirna is worse, but I have a feel like she is such a focal point of awfulness that a lot of our attention is drawn away from the fact that Charla is often just as ridiculous, entitled, and rude- to taxi drivers, airline employees, and other contestants... After the silly taxi-gate in Chile where both Mirna and Charla totally lost it (something which they're still griping about in insider videos, despite the fact that it is ten legs later), Charla says "beauty is sometimes skin-deep. It's easy to make yourself beautiful with plastic surgery, but to have a pure heart, and to have morals, is not easy to make up." Where the hell does that come from? Add in the comment she made in the last episode about the BQs padding their bras, and it seems she is one of the most looks-obsessed contestants in the history of the show.
Yes, Mirna is crazy, arguably the most obnoxious contestant in the history of the show... but Charla deserve some hate too. In her lame attacks on the looks of the BQs she comes across as petty and jealous, and she's not getting a lot of help from the Amazing editors, who have been spending an unusual amount of time in the past few episodes zooming in on the ghetto booty she is trucking around the world.