In most cases I have seen, the sellers do not disclose this type of work has been performed. The ethics of that is another topic unto itself.
For removed personalizations, look for the remaining writing to look off center or oddly placed. Sometimes you will see subtle hints of airbrushing that touches the edge of the remaining signature, or slight remnants of the removed writing that remain close to the signature. You may see slight over spray onto the red stitching and/or white spray into the holes of the stitching.
Finally, if you have the ball in hand, the paint should light up unnaturally under a UV light.
While the airbrush artists do a good job at color matching, what happens if the leather in the ball tones over time? I doubt the paint will tone along with it. Will you end up with a naturally toned ball that looks like it has white paint spots on it?