Why does the iso on my DSLR get worse as my camera gets older?

I've owned my Nikon D60 since 2008. It used to take some pretty nice photos at an ISO of 800. As it's gotten older the ISO quality has slowly degraded. Photos taken at ISO 400 began to look like they were taken at 800 and now images taken at ISO 200 looks pretty bad. It's so. Incredibly. Grainy!

Thoughts? Suggestions? Any help would be appreciated.

Are you shooting with your camera at its highest resolution, like RAW for instance?

Did you recently upgrade your monitor? A new or even larger monitor will show things about your images you could not see using a smaller or lower quality monitor.

I use an older Nikon D200 (three years older than your D60) and its sensor performs as well as it ever did.

In fact, RAW files I shot with it years ago can now be processed using the current ACR algorithms and result in even better image quality. My guess is that the problem may be in your workflow, NOT the camera itself.

You can of course send your camera into Nikon and have them do a recalibration and cleaning (about $250) and see if that works, but before spending that kind of money, I would look at the resolution on your camera and the monitor you are using.

When was the last time you calibrated and profiled you monitor?

Hmm it has been through a lot: beach trips, mountain hikes, rainstorms, snowy weather, and a few children with sticky fingers managed to get their hands on it.

When did you last have your sensor cleaned?

The camera is tired and need a vacation may be retirement

It's probably not. Sensors don't "wear out" or anything.
Now, it's *possible* that some other components are aging or malfunctioning (specifically amps or A/D circuits), but that's also unlikely.