Well it can be socially awkward to say, "no, I'm sorry", and it can be pretty much impossible for some people to say that. The fact that you're asking the questions means you're looking for a way to not say that.

So instead, just show them some of your older and / or lower quality work. That way there's no bad blood, and you're only showing stuff that's old news, and you are also convincing them that you're doing lower quality work than you actually are, which will make them be more comfortable and therefore easier to out-compete, if you're out do do that.