Most Helpful Guy
It depends on how honest you are. If you are stringing some of them along. Just having some fun while some of these guys are looking for something serious. Saying that the guy is "special" or "the only one" etc...
If you are frank and honest and everyone involved are in the clear and accept the situation then I see no problem. If not, then you are basically a light weight player.
Most Helpful Girl
Dating 'Different men' doesn't necessarily Mean she is a 'Bad' girl. This gives Her a Chance for maybe not so much Romance but to nurse and nurture a little fun under the sun, without being hooked at the hip. And a few could be friends to the end as well.
However, if she sleeps around with many a guy with a Try to get her in bed and Have Actually succeeded, she will obtain a Bad reputation which will Mean when a Good guy comes around in town, that She... Gets around.
Good luck. xx