When a republican brings up JFK and taxes they usually say Kennedy was a conservative because he wanted to reduce taxes on the highest incomes. That is easy to counter. Simply say – “Well sure, let’s bring taxes to where Kennedy wanted them to be: 65% on the top incomes and 47% on corporations.” Challenge them to look it up for themselves. They’ll keep using their talking point, but not around you, because you can just call them out on it anytime.