Quoting Andrea's Momma:" What do you think makes a mother a "bad" parent? Besides the obvious, like drugs, abuse, and neglect. ... [snip!] ... understand (Not abuse, like smacking and saying no) Having sex around baby I can't think of anymore. Just wanna hear opinions."
Apart from the obvious abuse and neglect, selfish choices..
I think it makes a person a bad parent when they knowingly
refuse to better themselves and/or their life.
To give an example: not toughing it out and getting the needed education in order to get a good job that pays at least minimum wage and is a stable one. Not wanting one. Not striving to be an intellectual and learn things. Lack of ambition to succeed in life, and the like.