How do you tell what kind of leather is on your couch?

There are several tests you can do to ascertain this.

Moisture test:

Put a drop of water on your leather (test in a hidden area first) - don't worry water is good for leather so will not damage it. If the water soaks into the leather and goes dark you have an aniline style leather. If the water sits on the surface you have a coated leather of some sort.

Some aniline style leathers will have a finish on them which will slow down the rate of absorption.

Scratch Test:

Most aniline leathers will scratch with your finger nail and leave a mark

These two tests are part of a 5 step process used as an industry standard for testing leather.

If you want more information there is a good flow chart here:

http://www.lttsolutions.net/whattypeofleather.asp

Credit goes to Tyler9552 for this great answer.