I'm not a stepmother, but my husband is my children's stepfather.

Someone asked me what I considered to be a good stepparent vs. a bad one.

A good stepparent genuinely loves his or her stepkids. Does she feel bad sometimes that she isn't the first to have had a child with her partner? Absolutely - that's normal. Resenting the stepkids for that: not normal. Resenting a birth parent due to their behavior? Again, absolutely normal! Making the children aware of your feelings of said birth parent: not normal.