That's a good question, mysnapz. It's hard to tell whether
a person just wants to share an image or whether they want
in-depth critique (like as if I would be able to provide
such a critique if asked!). You walk a thin line, though,
when offering critiques, because you risk pushing your
own creative ideas on someone else's project. Since I'm
the type that believes that everyone's creative personality
is unique (or should be), I'm very hesitant to jump in
with suggestions for changes, etc.

It becomes much easier when someone has more or less
specific questions about how to achieve an effect (and
I have an answer for that question).

Usually though, I just stay silent unless I really like
something, which might make me look like a back patter.