OK, I hope I'm not speaking too soon (touching wood etc) but since we changed to a two-night minimum stay, last September, I don't think we've had anything less than 5* ratings. [We made the change because we had a run of one-nighter/four-star guests.]
I don't know whether it's just coincidental... but my thinking is that:
many of the one-nighters weren't particularly up for/didn't have time to make a connection with us;
with the cleaning fee, the one-night price was relatively high;
they didn't really chill out/settle in/avail themselves of the facilities, eg kitchen. (I like it when people use our kitchen, feels like they're making themselves at home :))
It's a shame really, cos we met some great people who only stayed the one night, and I didn't really want to close ourselves off to them... but! D*mned reviews, eh 😉