Take a box of matches with you. In case of smells after your business or from the previous user, strike a match and dropextinguish it again immediately in the bowl. It doesn’t remove the smell, but makes you not notice it anymore.
This doesn’t remove the fecal smell, but the sulfur compounds from striking the match cover the undesirable smells. Therefore there’s no need to leave the matches burning for a while, simply lighting them is enough.