No one can tell you if they are good from a simple rundown like that. Clean them up and try them out. At worst you will have some or a lot of hang-fires and duds.
Agree...unless there are some photos it is really hard for the community here to give an accurate assessment of both the condition and useability. Even then, looks can be deceiving.
Last year, I shot some rounds that I bought, that were stored in an outdoor shed that was not heated, cooled, or humidity controlled. The rounds were pretty rough looking and looked like an overripe banana. Guys at my range / club looked at them and indicated similar sentiments as others here - as long as there's no pitting and such, it should be fine. Bear in mind that these rounds were subject to extreme temperature fluctuations between seasons from insanely hot to extreme cold - no doubt the exterior condition was caused by humidity through some of these environmental changes, and being stored in the original cardboard box, that would naturally absorb moisture as well.
If the OP's now-in-possession rounds were previously stored in a basement, unless the basement flooded and these cartridges were sitting in the water, what the OP describes may just be cosmetic in nature. Obviously it is hard for anyone to tell over the internet without looking/handling the rounds, but even then, we don't know what's happening inside. Shoot a few of them off and it will give you an indication.
As a side note, I used to store my ammo in my basement at my old house in a separate cabinet. My basement had no active dehumdification and the dessicant packs/containers in the cabinet basement went years between being put into the oven to respawn its usefulness (life and such got in the way, totally forgot about everything). Basement flooded lightly once during a heavy rainstorm and the carpet all around the cabinet was moist. Dried it quickly but years later, in checking out the cartridges, I could see where the moisture and humidity affected the cartridges. It was about 200-240 rounds of 9mm, and about 2800 rounds of .22LR (these seem unphazed). I have since shot all of them without problems. And they didn't even look half as bad as the ripe banana ones stored in an outdoor shed for many years.
There are members here who have shot WWII and shortly thereafter rounds without significant incident - and highly doubtful cartridges from that vintage were stored with temperature and humidity control in mind (not like there were things like AC and electronic humidifiers commonplace).
