If it were an error about a fact or facts, I'd want someone to call it to my attention. I don't particularly want to hear about typing errors (unless they change the meaning of a word or fact by being there). Something else I don't want "input" on are suggestions on things like how I could have made the Hub better. Again, facts are something very different from typing and/or writing style.
I think if someone sees what he thinks is a factual error he should send the persona a polite e.mail and say something like, "I noticed what I think may be a factual error in your Hub.". Then tell them the fact in question and why it is you believe it to be incorrect (or how you know it is incorrect). Closing with something like, "I just thought you may want someone to mention it, because I know I'd hope someone mention something like this if he found it in something I've written." Just one thing (and maybe this is me): I can't stand the obligatory positive remark that's intended to "cushion the blow" of the "negative" one (the pointing out of the factual error). To me, doing that amounts to a condescending insult that assumes I'm not professional, or adult, enough to be able to graciously accept having a factual error pointed out, or a fact I presented questioned. :)