-Bats fly into your hair

NOT TRUE, Bats have an extremely good sense of where they are going, even at fast speeds. Most bats use echolocation, a type of sonar, to navigate. Most bats eat insects. They, hopefully, are not going to find any in your hair. Bats don't want to get tangled in your hair anymore than you want that to happen.

-Bats are dirty

NOT TRUE, Actually bats are very clean animals. Bats are very clean animals, and groom themselves almost constantly (when not eating or sleeping) to keep their fur clean.

-Bats carry rabies

POSSIBLE BUT NOT LIKELY, Bats, like all mammals, can get rabies. Of all the rabies deaths each year, 99% are from dogs. Of the very few bats that do contract rabies, these rabid bats very rarely bite. If they do bite, they are afraid and are doing so in self-defense. Only about half of 1% of bats carry rabies.

-Vampires turn into bats

NOT TRUE, Vampires don't exist and bats don't turn into anything.

-All the pictures I see have bats with their teeth barred as if they're going to bite someone.

PERHAPS BUT NOT FOR THE REASONS YOU THINK, Bats normally will fly with their mouths open to either catch their dinner or because they are making high frequency sounds (echolocation) to navigate.

Some photographers will pick up a bat to take a picture. Of course, the bat is frightened to death and probably is barring its teeth in self defense. But bats are normally very shy, don't want anything to do with you, and will leave you alone.

-Bats will bite my neck and suck my blood

NOT TRUE, Only one species out of almost 950, drink blood. It is the Vampire Bat that lives in Central and South America. And the blood it prefers is NOT human blood, but blood of cattle and birds. These animals are not normally killed by the bats. All of the other species of bats definitely do not like blood.

Bats are wild animals. They will become very frightened if you try to catch or pick one up. Like any other wild animal, it will bite you in self defense if it becomes scared.

...Bats are actually very helpful to man and our environment.