Yep, highly recommend goo-off if you detect glue on the veneer. Rub it in and rub it back off with a clean rag. As Dave said, colourless rags are best! Personally I dont sand the veneer at all any more. Just a light going over with 400 to take off any raised grain after applying a small amount of water to raise it. Too much water and you risk unbinding the veneer glue and causing bubbles.

cheers,
Gav.