The first thing I would physically verify would be the depth of the pond. A shallow pond will be trouble with respect to out-of-control vegetation, FA (pond scum), turbidity maybe, and winter/summer fish kills.

I would also look closely for signs of drastic water level changes and any sign of leaks in the dam.

What kind of fish does it have?

Does it have bull head cats?

Does it have green sunfish?

Both of the above fish types can overpopulate and stunt.

Just a few thoughts for starters...you can really go to an extreme on pond inspections if you want to, but that advice would be beyond my experience level.

Fish on!,
Noel