Don't over-think it. It's not sinful to make a bit of money from a helpful tool. Don't even bother with the switch to remove the affiliate code, if your users c

Don't over-think it. It's not sinful to make a bit of money from a helpful tool. Don't even bother with the switch to remove the affiliate code, if your users can't grant you that, they can copy-paste the link and remove your affiliate code manually - that is, if they don't already have a browser plugin that does that for them.