Well, first, I'd make sure that you buy the conjugate REMOVER for whatever adhesive you use to put them on. If you get spirit gum, get the REMOVER. It should never be painful to remove something like this - and not using a remover can also potentially damage the ears (not to mention your own). Not removing built-up adhesive can also shorten their lifespan.
There's probably no reason to full-on wash them, just wipe out the inside if it looks like there's body oil or something in there.
Disclaimer : This post written by a Grumpy Old Man
Actually in the pipes:
- Remaking Ser Loras doublet.
- Luke Skywalker, A New Hope
- Wind Waker starter costume in swim material
Eventually: Paul from Dune, Faramir, Harry Sullivan