I know a bunch of you guys are gonna say otherwise and im sure some of you do really well with them, but they pretty much are. The use/benefit factor is not worth it. You're most likely gonna get most of your kills with your gun/scorestreaks so why not use those points to benefit your weapon or a perk?
I just can't justify wasting points on equipment that I'll rarely use when I use those points to help me in other places.
They are an annoyance which is enough reason for me to use them. I run BB/EMP x2 on every class with scavenger and after every kill I chuck a BB&emp. It's great because that stupid skull pops up after you kill somebody and people blindly rush the area.