Patrick Sweeney, over at Shotgunnews.com posted a good article about whether or not you should clean your suppressor.
The simple answer is “some need cleaning and some do not.”
Let’s start right out with the things you should never, under any circumstances, do.
First off, do not ever poke a cleaning rod, with a cleaning patch on it, down your bore and through your suppressor. If that patch falls off, you now have an obstruction. “Oh, it’s just a bit of cotton, it will burn up.” Maybe it will and maybe it won’t, but until it does, do you want it possibly getting in the path of the next bullet? And destabilizing it enough to thwack a baffle?
If you have a suppressor cranked onto your muzzle, and are loath to remove it, and simply must clean your bore, use a cotton swab that is a threaded-on rod attachment. At least that won’t come off inside your suppressor.
Patrick goes on to explain that most suppressors do not need to be cleaned and do not use aggressive solvents as some of them can attack metal.
The suppressors that do not need to be cleaned are typically the high pressure calibers. They are almost always sealed units from the manufacturer.
Patrick explains that shooting high pressure factory ammo will pretty much heat up and burn most carbon and self clean the suppressor. The photograph below is a cross section of a 5.56 suppressor with an extremely high round count.Reportedly it has had 148k round through it. It never needed cleaning.
Now there is an exception. If you shoot .22LR through your 5.56 suppressor. Some occasional rounds through the can is ok. But shooting an entire brick through the can is not advised. If you limit the amount of .22LR through your sealed can, then you can just go back to shooting 5.56 to clean out the lead deposits.
Here is an example where the suppressor was not cleaned out.
If you plan on shooting .22LR a lot, then just buy a dedicated .22LR can that can be opened and serviced yourself.
One caliber to pay particular attention to is .300 AAC blackout/whisper. Just like shooting .22LR and using 5.56 to clean out the suppressor, you can shoot .308 to help clean your .300 caliber suppressor after some discrete pew pews with your .300blk gun.
One other thing to keep clean is the method of attachment. If the suppressor is directly threaded on then you have nothing to worry about. If your can uses a QD attachment then you should make sure that the muzzle device is kept clean. Otherwise the suppressor can get stuck onto the muzzle device.