It is why I have never really fostered. I would be a fail for sure. We did once with a boxer for just a couple of weeks after she had surgery but she didn't like my cat at all so the decision to let her go was really made for us.
I would also get too attached and would be so depressed (I mean reallydepressed) from the sad stories. I will always have a rescue dog or two, but start my own bulldog rescue?--no. I would be a foster failure for sure too.