The Dark Side of White Dog

Veenie has many different nicknames in our home... Veenie-Bo-Beenie, Da Veener, Veen and Venus if she's in trouble. I originally named her Venus, and promptly stopped using that in public when someone at the dog park asked me in a very gentle, yet horrified whisper, "Did you really name your dog penis?"
You have to be very careful when using any variation of the V sound when she's around, because she'll pounce like a hawk. 
Hello.Hi.Yes.Hello.HiThere.DidYouNeedMe?  IBelieveYouCalledMyName.Hi.HeyThere.Mom.Mummy.Hi.Mom. HeySup.YouNeedSomethingI'mHereForYou.ICanDoAnythng? HELLO.HI.YOUSAIDMYNAME.
HI.

So when we want to talk about her, we simply use the term white dog, as a way to protect our faces from a doggie kiss attack. 
Veenie is a bundle of love, and I think she would probably lay her life on the line to protect the family, and I mean that. She's smart, but she has a major problem that, for the life of me, I can't figure out how to solve. She has a dark, and very mean side that she shows to male strangers. 
Veenie interacting with girls... no problem! When children try to pet her, she plops her bum down right in front of them, offers them her paw and waits for cuddles and pets. Men though? Men are a different story. 
She growls, shows her teeth, and barks like a rottweiler on the other side of a fence baring the words "beware of dog". You know that barking sound that guard dogs do when they are trying to take a breath in, but are still barking viciously? She makes that noise. It scares me, and I have absolutely no idea what to do to get her to stop. 
The worst part, as an owner, is that she is so damn cute and cuddly everyone wants to pet her! Who wouldn't want to walk up and pet this little girl at the dog park? 

 Ok well, maybe not THAT little girl, but this one....

CB and I took her with us when we went to have a few drinks at this outdoor bar in our neighborhood called 10 Bells. She bit two different guys who just were trying to pet her.  Now one guy kind of had it coming. I told him, in a polite way to back off, but he grabbed her out of my hands, picked her up and brought her to his face. I was just sitting there thinking... ohmygod ohmygod ohmygod.
Luckily it was just a tiny bite mark on each guy's hand, and both guys were super duper nice about it. That terrifies me though, because that is the kind of thing that will get her put down if she got vicious enough on the wrong person. 
I've tried yelling, I've tried not yelling. I've tried smacking her on the butt, I've tried staying calm and showing her that the person can be trusted. I just have no idea what to do to fix this. The part of me that doesn't have a home security system doesn't mind this dark side of white dog, but the truth is that I need to fix this somehow. 
Does anyone have any suggestions for me?