If your shower is spraying in different directions or looks kind of gross, that's almost always mineral buildup.

pour a few cups of white vinegar in a plastic bag, dunk the shower head in there, leave it alone for a few hours, and it'll come out clean.

you can shake it every hour to make sure the vinegar gets everywhere and the broken down minerals get out of the way, but it's not really necessary.

I soak overnight sometimes, but that's usually not necessary.

White vinegar leaves no residue, no smell, won't damage your rubber or plastic seals, is cheap and safe to use.

vinegar is crazy useful, I'm sure it'll make a reappearance in this community soon.

for clarification - this is the everyday, supermarket 5 to 6% acetic acid white vinegar, all the normal cheap stuff at the supermarket is that balance. Not agricultural vinegar, which has a much higher acidic level(up to 50%) and will damage anything you put it on.