Is There a Disruptive Camouflage?

When conserving a painting, does the darkened varnish that the original artist applied over the paint contribute the darkness of it? Darkness from age. It wasn't originally that dark. The question is, should we hire a conservator to remove that old varnish applied by the original artist to put a brand new clear varnish on it so that we can see the portrait more clearly and there's this huge unending debate about it.