TIPS FOR MAKING CARAMEL APPLES:

From Suzanne:
From my experience. Do not wash the apples..just brush them with a clean paper towel. If they have any moisture on them, caramel will not stick. Also, I melt in microwave with a tiny bit of water. Just enough to stir the caramel. The best ones I ever did were caramel, then dark chocolate followed by crushed peanuts dipped. You can also try and put them in the fridge to harden faster.

From Kelly~WA:
Your apples must be clean, dry and at room temperature for the caramel to stick.

From Janet/MO:
If the apples have been in storage, they're waxed. If they came directly from an orchard which hasn't waxed them, they still may have a natural wax, depending on the variety. The caramel also won't stick if the apple's wax coating hasn't been removed first.

Thoroughly clean the apples by dampening and sprinkling them generously with baking soda. Use the soda as a scouring powder, rubbing them hard and adding more soda as necessary. Rinse in hot water and dry well before proceeding to dip.

You also can try dipping them briefly in boiling water, which will melt the wax off. Again, dry thoroughly.