Some of them... I only clean them when they stop working.
The one I keep for home defense... I will up keep that a little more often.. they don't need to be as clean as you think... I run BCM uppers and BCG's on mine, they seem to keep on ticking no matter what I do to them.
When I DO decided to clean them.. I bring them into the parts washer at work for an other night bath... let them dry.. air hose them off.. then generally cover them with EEZOX. Seems to work great.