What is so intriguing?

Sometimes I wonder, what is it that is so intriguing to guys about girls who are quiet and who mind their business.
I can't generalize to everyone but there are always some group of guys who are extra curious.
In a professional environment, we come to work, mind our business, talk as much as needed and go. What is so intriguing about single girls? These guys have an issue with girls who talk as well and girls who don't as well.
College environment and office environment are different. Isn't it?