So reputation maniputaltion, asking for rep etc. isn't allowed. However, many people do it by leaving reps on people with things like "share rep" and "spread green" followed by their username. Shouldn't this be against the rules, as obviously the only reason you would do it would be to get the returned rep?
You can choose not to rep him/her. This way you won't get it again from him/her. Also, some people always spread their reps so as to rep the ones they like again because of the forum restriction which says that you can rep the same person only after so much reps for others or so. I find every post of Kerosene and few others in the forum rep worthy. I think it should stay that way. I always show my emotions in rep field.