Should they?
I would expect them to be somewhat self-cleaning when in regular use.

Also: Bonus point because Iiteral shower thought.

you need to rub the nipples every day.

Picking the mineral deposits out of ones that have become clogged is so satisfying.

1. This is one of the most shower-related shower thoughts of all time. Kudos!

2. A lot of people clean their bathrooms regularly. CLR or generic knock-offs are great for mineral buildup on faucets, drains, handles, etc.

3. My local water company regularly takes the main treatment system offline for maintenance and switches to the backup system. I don't know all the details but every time they do it the water is heavily chlorinated for a week or so, and this happens roughly every 6 months. So until I can afford to get a full-home filtration system installed, I bought a shower filter that goes between the water pipe and shower head. It needs changed every 6 months so I might as well clean everything while I'm at it.

Ziplock bag, white vinegar > toothbrush

If it's mostly mineral buildup just soaking it in white vinegar for an hour will dissolve it all and make it look and function as if it were new.

Nippled