As a general rule, I wouldn't say no. I would not, however, date some guy with a "Baby Mama." I don't want some woman who never had a clearly defined, committed relationship with my partner feeling entitled to constantly make demands or somehow think we're of equal footing with me in respect to my SO just b/c she had a baby. (I'm talking about something different from a divorced wife, an accidental pregnancy or a life partner with whom things didn't work out.) I would take into account as the relationship progressed how he dealt with his child/children and the health of his relationship with his ex-spouse. Someone who neglects or acts like a visitor with their own children and who constantly has drama with or talks badly about his former spouse speaks tons.
People have all kinds of baggage regardless of their age or marital/parental status. Some people in their early 20's aren't fit to date b/c their parents completely screwed them up. Some men in their 30's or whatever with kids are perfectly mature and emotionally stable. They just happen to have a child.