Could you get sick from kissing someone that's chewing tobacco?

Not contagiously: Using smokeless tobacco has no effect on the contagious potential of "swapping saliva". If you mean by "sick' the feeling of nausea, that is another story and a matter of personal taste and sensitivity. If by refusing to kiss someone who chews or "dips' they might consider dicontinuation of the habit then you have done them a great service.