clouding smudges or hazeing problem

[topclass]

I seem to have this hazy cloud smudge looking problem in my prints. Some paper give it more than others, mostly on thinner stocks and definitely on duplex jobs. I am not sure what could be the issue. Not sure if maybe a drum is going bad or the fuser or something else.It happens at random all over the prints. Machine i am using is a xerox 252.