J4 is a [statistically speaking] easy fold every time. what comes on the flop can be compared to coin flips: if you flip a coin 99 times and it lands heads up all 99 times, it still has a 50% chance of landing heads down on the 100th flip because every flip is independent of all other flips. likewise, every flop is independent of every other flop.
when people say "i called with my J4 because the jacks and fours have been hitting tonight," you can peg them as a fish or a gambler because they are using *superstition* to dictate their starting requirements.
that said, if you have J4 on the button, there are no raises in front, you have all the other players pegged as calling stations, you yourself are a conservative (tight/aggressive) player, there is the -chance- that you could bluff at this pot and take it down preflop. but it's not something i would do hoping that a J or a 4 hits on the flop....