Should we add icons made from people who have not given us their explicit consent?

I have received some icon submissions from people that didn't make the icons themselves and I haven't uploaded them yet. What is everyone's consensus about uploading icons that are freely available from other sources but haven't explicitly given us consent to host them here?

I would, of course, credit them, and if the creator is not happy with us hosting them and they get in touch with me I'd happily remove them.