BUT––the initial crud that builds up in a can helps suppress it––at least, to a point. After that (thousands of rounds), the crud decreases the effectiveness of the can by decreasing the volume and cooling ability of the can. And a little water––a few cc's (maybe 1/2 a teaspoon) will work––but trust me––it's messy and not really worth it.
Yes––.22LRs are dirty––but you don't have to be obsessive about cleaning, unless the can you buy is impossible to clean when it gets dirty. BUT––even with anti-seize on the components––if you shoot enough ammo, the lead vapor & vaporized crud gets into every nook & cranny & locks up the components.
Most sealed cans supposedly have an effective life of about 10,000 rounds, at least I've read that in a couple articles in Small Arms Review. So, in theory, a weekend shooter may not need to clean the can for their lifetime––it depends on how much you shoot.
All this said––I have 2 sealed .22 LR cans and an integral MkII pistol (2 are SRT & 1 is Gemtech)––the next .22LR can I get will most likely be a Spectre––once you start shooting a suppressed .22––you & everyone else you know––will want to try it, so it's easy to get to 10,000 rounds pretty quick. Or maybe a Tactical Innovations Quest––stainless-Mmmmmm––stainless. If I had it to do over––one of my cans would be servicable.
Just my $0.02––but hey––you asked