I think there's a useful subdivision here: people who can nod their head to rock music but can't get the rhythm in salsa, and people who simply have NO concept. I.e. people who have rhythm but can't "find the one" have an intellectual challenge of learning enough about salsa rhythms to be able to hook up what they are hearing into their own understanding of rhythm. Those who can't even clap the downbeats evenly have a different issue. I am hopeless at teaching this latter group because I have no idea what it is no to have rhythm. I also think the poor guy in the original post is suffering with confidence rather than with rhythm per se. A positive, relaxed mental attitude is incredibly valuable when learning anything, but especially when learning something that is driven by music. In my (beginner) class last week, I had a couple who spent the whole class saying "I can't!" "I've never done any sort of dance before!" "I'll never get it!" and I just wanted to strangle them. It made it incredibly hard to stay positive for the rest of the class. I was leading the woman simply in a basic step and she kept burbling about how she couldn't do it. "Have you heard of affirmations?" I said "No! I haven't done any style of dance." After the class they said they had had a great time and would definitely be back. Go figure.