What are the normal signs of a viscous fan clutch going bad? I've been hearing some low level grinding or growling noise at start up and some random clicking sounds after 30 minutes of driving and it sounds like its coming from the fan assembly.

Pull the belts, start it up, see if the noise is still there.

If not put the belts back on, put a stethoscope on the various accessories and narrow it down.

Yep, that is the same root-cause path I have planned for later today but wanted to ask the obvious since I've never had one of these before and am just not at all familiar with their failure mode/s.

Long before they go completely out, they get looser at low speed. I have fought some over temp problems in the past that turned out to be the clutch not moving the fan well enough at low engine speed. Consequently, I replace my fan clutch every few years. For the $50 or so, it is cheap insurance.

Having said that, I personally haven't had fan clutches make any real noise as you described. I am not saying that they can't, just that I haven't experienced it myself.

How old is the fan clutch and with the engine off, how tight or loose is the clutch when you move the fan? There certainly should be no fore/aft movement when moving the fan.

I'm sure you've seen articles like this.

Viscous Clutch Troubleshooting

yeah, that was the first thing I noticed too. the temp creeped up on the car while driving. never did hear any noise.

I will say if you find the clutch went, replace the water pump too.
I didn't do that and had my fan drop into the rad and had to have that recored. very expensive fix for something that would have been cheap to take care of at the time.