> I try my best to make her have all 4 feet on the ground but people just say "oh its all right, she's just so sweet" in spite of my telling them im trying to train her.
I will hang my head in shame now as I should know better, but I am one of these people. I keep telling myself to ignore peoples dogs unless they are behaving 'nicely', but I just get carried away and don't think about what I'm doing untill the dog has jumped up :( Only this evening, as I was coming out of a shop there was a bloke with a great dane, the dane pulled towards me (in a friendly, 'I just want to say hi' sort of way), so I couldn't help myself saying 'ahhhhh, hello baby, you izzzzz lovely' in a squeecky voice as I tickled his chin
(LOL, to the dog, NOT the bloke!!),
it was only when I saw the owners face, who was desperately trying to stay on his feet, that I had been naughty and encouraged 'bad' behaviour again :( :(
I also see this from the other side of things though as Buster (Mastiff) used to get VERY excited when meeting people, to the point he would stand on his back legs and pull me towards them

Some people honestly don't mind being jumped on/slobbered/muddied by a dog and don't mean to be a pain in the bum (like me) as they understand dogs will be dogs. The fact that people do this DOES help your training in the long-run as you will have to teach her manners even with people stroking her when jumping up. It can be done :)
With Buster I would make sure I had treats (cheese) at the ready and keep feeding him bits of cheese & giving verbal re-enforcement as long as he stayed focused on me or sitting nicely. If he was really getting stupid I would ask the person, politely, to step back and 'don't touch him again until he sat down as I'm trying to teach him good manners'.
It's not a problem meeting people now, allthough sometimes he still needs reminding if he gets excited, but I'm amazed at the difference compared to what he used to be like :)