Larger machines use dildo attachments and you should get 100% silicone toys instead of PVC, "jelly", or so-called "true feel" TPR/TPE.
These sex machine dildos are removed from the machine, so you can wash them after using them, just like you would wash (and/or sanitize) a regular dildo. 4 If you get a orgasmangel machine with Fleshlight attachments, then Fleshlight and similar masturbators are porous, but not as dangerous as TPE dildo because they don't get inside the body. However, they require more careful cleaning than silicone; Check out how to clean a Fleshlight or similar male masturbator here.
Also note: The hand-held plug-in dildos mentioned above are not waterproof, so be sure to clean them carefully. You'll want to wash your velvet propeller or bare machine in the sink so the infrared vents don't fill up with water. Don't use any sex machines in the shower. If you want a waterproof pull-in toy, check out the Stronic Pulsator range (reviewed here) or the Lovehoney Happy Rabbit Vibrator.