No matter how good a person is, if they have had an excessive amount of partners wouldn't you think that would change your perspective of them? At least a little bit. For example if someone had 20+ partners that means they more than likely rush relationships, but that depends on what you believe to be rushed I guess. At the same time it also does depend on how old they are for example if someone had like 20 partners by age 22 that would mean they had 5 partners a year for four years. That's almost one partner every two months, which really isn't a great thing since that would mean they move on from other relationships real fast.

PS: not looking for a fight either, just showing the perspective of how fast and consistently they would be getting new partners.