In a perfect world where there are no loose running dogs, potential problems with male dogs trying to seek the company of a female in heat would be greatly reduced but alas that's never going to happen in my lifetime!
But it isn't as bad as it was many years ago before leash laws came into being - it can be bothersome though.
However, even in a perfect world, it is much better healthwise for you to have your furpal spayed. It will eliminate not only the hassles of having to deal with heat cycles but will eliminate the potential for some types of cancer.
I have always had my dogs spayed/neutered at 6 mos. But alot of the vets today do it much earlier.