I often get emails asking about when to get waxing in relation to another spa treatment, especially a body scrub. When booking appointments the receptionist should alert you to any conflict of services and advise you the best way to book and space your treatments. But often the receptionist in unaware of conflicts or just in a hurry. A red-flag on the day of your appointment from the technician has to make them choose between taking and risk removing hair when they shouldn't or losing income.
Lightly exfoliating before a waxing or sugaring usually does help on the body because it gets rid of dead skin cells and helps the hair come out easier. So depending on the type of body scrub and your skin type, it may be harmless to have a mild scrub sometime before a body wax/sugar, preferably not right before though. And definitely no scrub services immediately after as this could really sting an irritate the skin- especially using a salt-based product.
We have to keep in mind that waxing also exfoliates the skin. Sugaring does as well, but not to the degree as waxing, and doesn't stick to the skin as much. Having an intensive body scrub on the same day may be too much exfoliation altogether and be disastrous. It could lead to the removal of skin, bleeding (more than just spots) and scabbing (see more waxing precautions).
Ideally, it would be best to get a vigorous scrub at least three days before or after body hair removal services.