I'm pretty sure if a company asked me to implement a feature for them as part of the interview process and didn't offer to pay me I would know up front that it'

I'm pretty sure if a company asked me to implement a feature for them as part of the interview process and didn't offer to pay me I would know up front that it's a bad company. Maybe you have a point that it is a good "interview" since it flags the place as a crap hole.