Here's my opinion on this, I really don't care about local processing all that much. As far as I know, I only have 1 clip that might have been recorded off the internet. I don't mind webchecks as long as I can't tell they were recorded off the web. This means for fm stations, you need to use the highest quality stream available, usually the AAC. There are also some stations that I wouldn't accept airchecks from for this reason, most notably KORQ or KMVN. Unless it's scoped and the station cuts off the commercial late or comes back a little early, also make sure that the commercials on the station transition smoothly. On AM stations, record it off the air with the exception of KITI, whos stream sounds like the AM signal anyway. Also, be mindful of any background music on the stream. There's an aircheck of WRQX from 2010 that I can clearly tell was recorded off the stream because they had background music or something playing on the stream at that time.