Bond Nature

Let's take a look at the nature of each bond in DMSO.

O=S: 3.5 - 2.6 = 0.9

The double bond between oxygen and sulfur is a moderately covalent polar bond.

S-C: 2.6 - 2.5 = 0.1

The single bond between sulfur and carbon is an extremely covalent polar bond.

C-H: 2.5 - 2.2 = 0.3

The single bond between carbon and hydrogen as a very covalent polar bond.

--Note that all the bonds are covalent polar bonds.