scratchiness on older lp's

Surface condition does not necessarily reflect the amount of groove damage that may have occurred.

I've heard records that look great but sound terrible and vice versa.

Beauty is only skin deep.

You do not need to get the lable wet at all.
Just allow the LP to lay flat and drip the solution into the grooves. It will stay in the groove area. Just keep it from drying up while soaking
The one point you might get some water on the label is when you pick it up and tilt it to go into the spin clean. Just have a paper towel ready to keep the label dry.
(at least half the labels are actually waterproof, most are somewhat water resistant. only a few really are water, die instantly..)

If it is a buildup in the grooves your stylus should be digging it out. If your stylus stays clean the record is most likely damaged.