People have been using clear acrylic sprays of varying types since printable discs first came out.
Yes, you can easily render a disc unreadable with over-spray.
The watershield / aqua-ace type glossy finishes don't really need a spray.
But given the cost of printable discs these days, why spend money and time messing with sprays? If it wears out, replace it. If you really want gloss, start with glossy discs.