Consider this from typelogic:
Extraverted Sensing
Sensing is extraverted. ENFJs can manage details, particularly those necessary to implement the prevailing vision. These data have, however, a magical flexible quality. Something to be bought can be had for a song; the same something is invaluable when it's time to sell. (We are not certain, but we suspect that such is the influence of the primary function.) This wavering of sensory perception is made possible by the weaker and less mature status with which the tertiary is endowed.
It seems like a FeSe loop can be an overvaluing of things perceived through the senses. Example: these ENFJs may seem shallow, obsessed with their image and material status or maybe they adopt an ascetic attitude towards material things. It might even appear very inconsistent to others, where the ENFJ seems to value some things & not others without any discernible principles behind these feelings. Or they may indulge in hedonistic pursuits to block out their own feelings - their alone time with Ni can result in a brooding that they're trying to avoid.
I also think here is where we get the "manipulative" ENFJ people talk about. It's basically the flip of an ESTP Se-Fe loop, which is probably what is behind their used car salesman stereotype.
Fe is a thought process which is very adaptable in the sense that it accommodates the people around them, knows how to affect them, picks up on their vulnerable emotions, etc. Se is a thought process that sees tangible clues easily - it may aid in reading body language, for example. Se people will act on the immediate options they see - adjusting their approach as they go according to the sensory signals they pick up & testing what they can get away with. Combine all that with the Fe inclination to read people emotionally, and you have someone who can easily affect others. They may know how to set someone up for the response they desire. This does not have to be used for evil, but even if it is not, it can seem manipulative to people who fall for it.
I have an ENFJ friend who is definitely NOT manipulative. I would never define him with that trait, but I will say he knows how to get a rise out of someone if he wants to. This is also what can make ENFJs good at banter & teasing. I think the Se adds to the playful side & is positive when its anchored by Ni.
The Fe + Se loop may also cause an ENFJ to gauge their moral standards by whatever their current atmosphere happens to be. Everybody else does it, so it can't be that bad. Ni provides an insight beyond the moment, unveils the principles behind Fe so as to not blindly follow whatever seems good at the time.