I think this whole story of Meigh being fucked by a paid guy in Mexico is complete horseshit. Total.
To me, it sound like as preemptive strike against Meigh for when she reveals that it was in fact Ethan that took it up the ass.
In any city on Earth you'd find thousands of guys willing to fuck a chick up the ass for nothing, but here we are supposed to believe they paid a guy. horseshit. Just horseshit. Ethan don't spend anything on anyone other than for his own food, alcoho, drugs and hookers for himself.
It's Ethan being preemptive. He's the one who got fucked up the ass, I am certain of it so that when it comes out, he'll claim it is just a "revenge story" against him. Such a shallow attempt.