After you've set a new bathtub in position and fastened it to the wall studs, it has many opportunities to catch falling construction adhesive before you take your first bath. The most common source of adhesive spots is drips that occur during installation of vinyl paneling, but the spots can also happen during trim installation. Construction adhesive sticks really well, and it's strong, but it's easier to remove than you may suspect. You can usually loosen its grip to the tub walls with a lubricant, and once the bulk of it is gone, you should be able to scour the rest off.
Coat the adhesive with petroleum jelly and wait for it to soften, which may take several days. Use mineral spirits as an alternative, but you may have to reapply it once or twice before the adhesive will soften.
Heat the adhesive to 140 degrees Fahrenheit, using a heat gun, if you don't have time to wait for petroleum jelly to work. If you don't happen to have a heat gun in your tool closet, a hair dryer set to high will also work. Keep the heat on the adhesive until it softens.
Scrape off as much of the adhesive as you can, using a plastic putty knife. A plastic knife will scrape effectively, and it won't scratch the finish.
Scrub the residue with a mildly abrasive cleaner, such as a paste made from baking soda and water. You can also use scouring powder or, in a pinch, white, non-gel toothpaste. Wash with clear water when you're finished.