Yeah, well if good intentions were equatable to intellect Andrea could've found herself out of that position numerous times. Ultimately, she still chose to blindly trust a stranger with a walker in the closet, rather than trust the instincts of someone who saved her, cared about her, looked out for her, & probably taught her a great deal for nearly a year.
Wanting to save people's lives or keep people from dying had less to do with that decision than her wanting to have a "Normal" life again. Make no mistake, it's not just because she was trying to save people, it's also because she"Turned her back on a friend for a warm bed". That line of Michonne's may have been a bit over simplified, but at its core it is true