I killed a spider that was in my living room a few days ago and for reason I always feel bad when I do it, given how I've always been told never to kill them as they are supposed to keep flys away. However I think they're utterly filthy and just want them gone as soon as I see them.
I also saw one in a house I went to view a few weeks ago. However I left it alone. Maybe it's part of the fixtures and fittings.
So which bugs do you squish and which ones do you leave to fight another day. Flys, moths and Daddy Long Legs get the rolled-up magazine treatment from myself personally.