70% are just "Hi, how are you, my name is x." Why would I respond to this? Put in some effort. You're trying to make a first impression.
Another 20% are creepers, and thus end up on this blog.
Then another 8% are things that are at least somewhat offensive, like "Well my dear, for a "brown American" you sound pretty awesome." You don't know me. Casual -isms aren't going to work. Negging never works, even if you do know me. Stop listening to PUAs.
And then maybe 2% are messages worth reading.