Some dogs are just naturally aggressive no matter what, while others are naturally submissive. Socializing won't really change that.
The idea behind socializing is that you want them to be exposed to different people and dogs, so the dog learns what's normal behavior verse what's threatening behavior. For example, your child kissing the puppy on the face shouldn't be seen as a threat.
In a way dogs are like people. No matter how many people you met in school or through out your life, you don't actually like everyone you encounter. In fact, a lot of people you probably hate within seconds of meeting because you can just tell what kind of person they are,
The same is true with your pup. There will be dogs that your pup will not like no matter what and that's okay. The goal is not to make them like everyone and every thing, but simply be comfortable and not scared. You also want it to learn how to approach other dogs so it doesn't get attacked.
For example you never let your dog rub faces with another dog, especially if they are on a leash. Butt sniffing is okay, but face sniffing is not. If a dog isn't socialized and makes the mistake of face sniffing, it could easily get bit. Another benefit of socializing is that the dog gets to play with other dogs. And when dogs play, they play fight. The more play fighting they do, the more confidence they have because if they ever do get into a fight, they'll know how to handle themselves. Just be sure to keep the play fighting in play mode. If your not sure or you think your dog might be over excited, simply call your dog, have it sit, then release it and let it go play again.
Last thing is that socialization doesn't have to cost you anything. Most Petco stores offers free puppy socialization. If you go regularly you'll also find out what dog parks to visit and what dog trainers really know their stuff. You can also find free puppy training videos and lessons. Dog Star Daily's website is my favorite (
http://www.dogstardaily.com/). I also like the video called Sirius puppy training.