I will come right out and say it: I have had alot(like, ALOT) of sexual partners in my 26 years of life. However, I have ALWAYS practised safe sex, unless i was in a committed relationship where both have been tested. Of course, there has been the odd indiscrimanate time(I do have a suprise 14 month old after all

).
Personally I don't think there is a thing wrong with having multiple or single or no or any partners. Its all personal choice and you do what makes you happy.
With that being said. Most of the partners I had before the age of 18 were had for the wrong reasons. At that point I was still looking for love in sex. When I was about that age, 17 or 18, I had a change in the way I veiwed sex and love and gained alot more confidence. Thats not to say i could have been considered no longer promiscuous or whatnot(i hate that word - it makes it sound so wrong to be sexual). Personally I dont put much stock into labels like that or the nasty things people sometimes call each other.
As long as you are doing whatever you are doing because you enjoy it and for the right reasons, and you are being safe and getting tested no matter what regularly, I say do what your heart desires. Sex is a healthy thing if done for the good reasons.
I've been a part of the alternative scene for a good peice of time now, so I tend to be much more open minded about this stuff.