What parts are used from wet iphone?

I've noticed a lot of people that fix iphones still buy wet iphones for i don't know what reasons. I've been wanting to start up an iphone repair business as a side job for the mean time and i've been so curious to know what people do with wet iphones.
Do they have some parts you can use? Screen still work?

Sometimes the entire phone is salvageable.iPhones are incredibly well built and even after complete submersion in water the device will still function 100%.
Minimally the entire body; the front and back glass, the bezel, etc can be used. From my limited experience the camera, speakers and the battery can be salvaged as well depending on how long the phone was wet.
If the phone was not submerged and only the water damage indicators are triggered the entire phone can be used after being inspected. The indicators are simply warnings that there may be damage or damage could occur over time if the water is not removed and corrosion starts to destroy the metal in the electronic components.
To the average consumer a phone that has gotten wet is pretty much junk and are looking to recoup any money they can to replace the phone.
However, phones that do not appear to power up may actually have a fully functional mother board and only a bad LCD or a bad charging port that won't charge the battery and so on.
There's a large and growing market for used and damaged iPhones that is not going anywhere anytime soon.