I can vouch for the fact that they will ban you for glitches, I did the prestige token glitch got banned for 48 hours and had everything erased starting back at level 1 lost all titles etc, plus they start you at 1,000 losses and 10,000 deaths so your KD will be 0.01 for a loong time.
it sucks because i legitimately got to 9th prestige without it but i thought i wouldn't get caught. Well jokes on me becausse I did get caught but oh well i have an alternate xbox live account and i use that one for mw3 now.
word of advice for anyone whos ever wondering about doing a glitch in this game they will ban you this time robert bowling isn't trolling he actually means business :/
My proof: old gamertag is "Dreadnaught 808" look me up on Elite to see the result of getting banned.