I assume side ribs are the same as spare ribs. When I get fatty spares, I trim most of the fat off. A little fat adds moisture and flavor, but a lot of fat makes them hard to eat, IMO.
Take a sharp, fine cutting knife, and trim off the excess fat.
So much of the beef and pork we eat comes from factory farms, where the livestock is fed chit it was never meant to eat, just so the big corporations can make more money, that you are bound to find more fat than you need/want. Fat = profits.
I just read a really horrible story about factory pig farms in Canada. Caveat Emptor.