I saw this how-to awhile back and when I bought this is a pair of dress heels for $2 at a thrift store, I thought I would try this out.

While the tops looked great, the bottoms were scruffy and the thrift store had written the price on the bottom and I was not able to scrub it off, so I decided to give this a try and it turned out very well.

Items that I used:
Acrylic Cherry Red paint
Sponge Paintbrush
Clear Coat Spray Acrylic
Masking tape (optional)

I would suggest using masking tape all around the area near the sole of the shoe before you begin painting as it will prevent you from getting paint on the shoe - I didn't and although I as able to wipe off the red acrylic paint because it was still wet with no problem, when I applied the clear coat spray, it over sprayed and it caused the vinyl on the side to bubble up a bit, but fortunately, it is not too noticeable.

You paint the bottom of the shoes with the red acrylic paint with a sponge paintbrush - I used 6 coats and allowed the coats to dry throughly between coats (about 30 mins).

I then sprayed on the clear acrylic paint as a sealant and to give it shine.