Do you mean the games aren't the time control they claim to be, or that someone is using the custom time control of 15:5?
Why does chess.com offer 15:10 games, then sometimes they are 15:5?

on the web version of chess.com, 15:10 is a standard drop-down option, but on the iPhone/iPad version of chess.com, 15:5 is a standard one-click option.
ahhhh. this explains a lot. so when i'm playing on my iPhone, am I just playing against other people on their iPhones and iPads??? This would make a bit of sense because on my laptop i keep the opponent window between -200 and +200 of my ranking. yet, on my phone i will get crazy mismatches vs players 500 points above or below me.
just wondering why when i play live chess, sometimes there's the 15:10 option, but sometimes it's 15:5. just seemed weird. anyone know?