Even if you're very careful about what you put down your drain, it will still inevitably clog at some point. Minuscule particles, soap residue, and oils are some of the substances that will eventually build up and cause clogs.
If you detect unpleasant, sewage-type, odors coming from your drain(s), it is a sign of a partial blockage, which will only get worse. Before you call, try pouring baking soda into the sink drain, and let it rest. If that does not get rid of the smell, then the drains need cleaning.