Show vs. Tell (How far do you go?)

Most of us writers have heard the big lecture "Show vs. Tell"...

Many of us have heard at least once in our critiques that "you do a lot of telling... don't tell me the man entered the room, show me..."

How you define showing vs. telling can sometimes be a little tricky. Many times I try to show as much as possible, but I still end up hearing "you do a lot of telling.."

Obviously a phrase like "She was happy" is telling. But what about "She smiled"?

After all the verb to smile is a fairly active verb. Still some would consider saying "She smiled" as too generic.

There are some critique readers who would say: Don't tell me she smiled, show her lips smiling.

So then, you end up writing more detail, perhaps something like this:

Her rosy lips brightened. The edges of her mouth curved upward.

Critique person: You do a lot of telling. Don't tell the readers her lips are rosy. Show us. Also don't tell us her mouth curved, show us how it curved. And you shouldn't use adverbs so take out "upward"... Also no adjectives, metaphors, similes or 'to be' verbs.

The question is, depending on the context, unless the way she smiles is unique and super significant, is it necessary to go into detail, or is it sufficient to say "She smiled." ?

Of course there is the issue of flow and pacing. After all, if we already have a picture of the character established by previous description, can the readers imagine how she smiled in their heads?

Don't get me wrong, details are always fun. Some will nitpick whatever you do. (Of course at times they may be correct.) The question is how far do you go?