MOABs I've earned in Infected (3 on day 2 of Infected when Throwing knives were not around) were earned legit by holding off the hoard with random teammates.
Since then I've seen countless people boosting for MOABs and trying to boost for MOABs.
Guys if you see people doing this, REPORT THEIR ASSES!
In COD report it as Boosting.
XBL > File Complaint > File Complaint > Tampering > Cheating > File Complaint, then just for fun, and to make sure you don't run into them again, avoid them (Game Behavior > Unsporting conduct).
I know you can report players to SEN, but I am not sure how as it's been about a year and a half since I've played a MP game on my PS3. Been playing offline on it. 3.72 FW