3 Answers

There are a couple of red flags when it comes to having a cop for a boyfriend.  First of all, they are notorious as a group for being unfaithful playboys.  That's not to say ALL of them are immoral, but there is a significant number who are.
Next, they make a TON of money and their retirement benefits are HUGE.  If you were to marry a cop, it is most likely he would want a pre-nup, to make sure he did not lose any of that fat retirement check if the two of you divorced. 
Many cops have a tendency to bully, be domineering, and intimidating.  You don't want to put yourself in a position where that personality manifests itself into your relationship.

There are probably good points in having a cop BF but I don't know what they are.

I dont see any reason why not , they are still human.

They have extremely stressful jobs.  If they have learned how to handle stress in a positive manner, rather than taking it out on their loved ones, then they may be.  That can apply to anyone in any stressful occupation though, can't it?