My oldest son uses a few basses from the herd, and really loves this Koa/Purpleheart Peavey Unity. He always treats our gear well and I have no problem lending him any bass or amp I own.
Unfortunately, a band member or two thought it would be funny to slap on a sticker they found on the floor at their last gig. Opened the case, slapped it on, and closed it. He's pretty pissed off and ashamed, and rightfully so.
On the upside, the top-side of the body was starting to wear, and I was planning on sanding it back and re-oiling it later this year, but this kinda gets me mad (which is pretty hard to do). I know this is an easy removal job, but the whole situation makes me wants to clunk a couple of heads and give them a life lesson about other people's stuff.
It doesn't matter that it's not a boutique bass, what matters is that it ain't yours
How about one of these options:
a) If you know which band member put the sticker on, calmly walk into their next practice with a can of neon spray paint (something obnoxious like neon chartreuse). Ask to borrow the pranksters' guitar, drum head, amp head, etc. When they ask why, explain that they defaced the front of your bass, so you get to mark up an equal portion of their instrument. Again, do this very calmly and matter of fact. Show them the obnoxious paint color. When they freak or object that that is not cool, explain to them "you would not want it on your own gear, so please don't do it to other's gear". Also explain to them that you fully support their band, but if you can't feel safe about your gear, the you will NEVER lend any gear (bass, PA, stands, mics, etc.) to them in the future. Then calmly walk out and go return the unused paint. But point made.
b) If you don't know which band members put the sticker on, calmly walk into the next rehearsal and hand them an invoice for time / materials to clean and restore the bass. Explain that you are treating them as adults and as adults, when you damage another person's property, you have to pay to fix it. If they object or ignore the invoice. Ask them, if you were to go out to the guitarist's car (or whichever band member has the car they cherish) and smash his headlight, would you all just chuckle or would he expect to be reimbursed for the repair? If they still object that it was just a joke, tell them it took time and money$$ to fix the bass just like a broken headlight. Again explain to them that you support their band, but if you can't feel safe about your gear, the you will NEVER lend them any gear in the future. Up to you if you want the band to pay the invoice or if you feel they felt contrite enough.
The whole point is to help them realize boundaries. Since you said they are good guys (they don't frequently intend to damage or harm others stuff), it would help them as adults to realize that pranks can be fun, but pranks that cost people money / time are not always "painless". So they will next time think about how far to take a prank.
Hope the clean up works out ok.
