Yes, absolutely for 120V AC and nearly as certainly for DC lights. I'd do a bit of study to see how a DC dimmer is set up first, though; it's quite possible that the brains of the dimmer are separate from the switch and, depending on how things are set up, it may take something other than a plain switch to bypass the dimming function.
I wouldn't think that most DC LED bulbs would have trouble with a dimmer, whether or not they're officially rated to be dimmable. This is definitely true for the less expensive ones that use a plain ballast resistor or linear regulator. Ones that have some sort of a fancy constant-current switching regulator might behave less predictably with a dimmer that is also basically a pulse switching gizmo.