The answer to 'my drain cleaning smells bad' is that a smelly drain is often caused by a buildup of organic matter, such as hair, soap scum, or food particles, that is decomposing in the drain. This can lead to a foul odor. Common symptoms include a persistent, unpleasant smell coming from the drain and potentially slower drainage.
There are a few potential solutions you can try before calling a professional plumber. First, try using a drain cleaner or baking soda and vinegar to help break down the buildup. If that doesn't work, you may need to use a plunger or a drain snake to physically remove the clog. However, if the smell persists or you're unable to clear the clog, it's best to call a professional plumber, as they have the right tools and expertise to properly diagnose and fix the issue.