Unsavory smells in your bathroom are never a good time. There can be several causes for unpleasant odors coming from your toilet in particular. One possible reason to check is the slope of your drain line. If the pipe doesn't have enough slope, waste and water will collect in the pipe instead of draining sufficiently. The same problem will happen if the inside of the pipes are rusted and waste doesn't have enough space to properly flush away. Call a Smart Plumbers service technician to check on your bathroom drain line if you suspect any of these problems.