Songs don't get tested before becoming new adds. You have to play them 100 to 125 times for the average listener to hear them even 5 times, and that's about the point at which a listener has either bonded with or rejected a new song.
We do have lots of support for adds, such as the trades, the airplay monitors and our own networking. So if we are uncertain, we can watch other stations before making the add. And sometimes songs we did not think had potential get adds at stations we respect, so we take another listen.
One thing most of us ignore is the whining from the record ducks. There are so many ways they can try to play us... my "favorite" is "... if I don't bring this song home, I am going to be fired". The worst one is when the duck asks to drop a previous song by their artist which is working great so we can play the unfamiliar new song only because it has been 12 weeks since the good song came out.