I agree with Dick Greehaus. The purpose of a singaround is to share music not be a topflight performer. I admire anyone who has the nerve to sing in front of people because I personally know how hard it is. First of all, one who studies this kind of thing is usually their own harsh critic. It doesn't have to be amplified by some half-knowledgeable outsider. Any criticism I've received from someone who is not actively engaged in music or singing has never been valuable.

Only those with an ego-driven agenda would offer gratuitous criticism to anyone attempting to sing in public.

There are those other ego-driven amateurs that are pushy not knowing what they don't know who are hard to tolerate but any helpful criticism would be lost on them anyway.