Diamond Mom,
"...best way to answer without ticking off the scouts?" What you need is information.
Professional scouts have "ranked" your son estimating what round he will go in. It can/does change as the draft date closes in. They use various numerical systems, but basically come out with a result. Some are more sophisticated than others, i.e. using computer programs, etc.
I simply asked the scouts, when they asked round and $$ questions,"...where do you have my son going?" What this did was give me an idea if this scout was truly an advocate for my son and if the various scouts had similar opinions of his ability. I needed to know if their opinions and our expectations were "matching".
Not one scout declined giving me the information. A few pulled out their computers and actually showed me the tracking information and ability ranking systems they used.
Once I had this information, we could talk and discuss the future possibilities on a "more" level playing field. Bottom line, the scouts my family worked with were all professional and willing to share information when asked. Good luck to you.