in boredom and on topic, to spot a hacker:
1) If they are 15/50 (15th stige, level 50), usually you wanna check (easy to see by looking at their name
2) If they have a **** load of CoD Points, then you dont even have to bother checking, they ARE a hacker
3) Upon checking a 15/50's profile, if they have less than 8 days, generally they are a hacker, 7 days is cutting it close, but usually passable, 6 isnt
4) If it says they have 8+ days but less than 1k matches (add total losses and total wins) generally means Hacker
5) Next, you check their KDR, if they have anything less than a 1.0, assume they are a hacker, anything higher than 4.0, usually means hacker as well (i doubt anyone legitimately has that who is also 15/50, but its always possible i suppose)
6) If their kills do not break 20k, assume they are, I typically assume so if they don't have 25k, but if they always play the objective, its possible I suppose
All of these are easily hacked, the one thing I know of however that is a sure fire way of checking, is this:
7) In the weapons tab, go over to Kills With, check to see if their kills match up, they never will as Kills with does not include Killstreaks and accessory tools (lethal, tactical, equipment). However, if it says someone has 50k kills and you see they have 2k kills with their most kills weapon, thats a VERY good sign. Easiest to tell if someone only uses 1 weapon, but typically if they use more than 1, such as myself, round it, instead of 1300 kills, say 15, instead of 590, just say 5 or 6 (smaller numbers make for quicker math), I personally round to the nearest 500 usually and if it isnt within a reasonable amount, then they'v egotten caught. Checking equipment and killstreak kills to help make this more accurate, but doing weapons will give you a general idea so you can check the next possible hacker.
Anything else I am missing?
Damn. You got me. 
