I'm a ham radio operator as well and have a good understanding of how apps like this work. The quality of what you hear on each of the hundreds of available streams depends entirely on the person providing the audio for that stream. For each one there is a radio receiver picking up the local transmission, which then feeds its audio through an internet connection where it is streamed through the app. If there is an issue with a particular source or stream it's usually on the originating side and not with the app, all the app does is gather these streams together from around the world to make them available in one convenient place.
I've been using Scanner Radio for a long time and it's a great app.