Lost my first reply as well.
It went a little something like this.
I found it confusing reading through the responses on this thread as to what comment you were concerned about. To be honest, I completely ignored the fact that you said the girl was pretty. I thought it was the comment/joke at the bottom.
I do not think that it is wrong for you to say that a portrait of a young lady makes here look pretty/beautiful/gorgeous. These are all words that would be used if you met the parents of a baby in the street (along with all that coo-ing etc. that goes on). I think that any parent should see this as a compliment, (and I suspect that some parents are blind, there /are/ some pretty ugly babies out there).
[edit: On my second thoughts, if the young lady in question were in a more provocative pose, then perhaps there would need to be cause for caution, however, what is the parent doing asking the person to be in that pose, and then posting it]
(joke is not the correct word here, but I cannot think of the correct one). My first thought was the comment you had left at the bottom of the pose. And whether it was incorrect to be bringing to mind that this does occur. However, I believe that you know the person who posted the picture, and that they know you, and would take it in the terms of the 'in-joke' that is on this board. I would think twice about posting this comment with someone who didn't know me and my sense of humour. It is a bit like a racist joke in a way. There is a chap at work who is Polish (my ancestry is as well), there is no reason he can't make a joke about the state of plumbing in Poland. There is a context, and although this comment is riske (with a grave), and a bit of a taboo subject, it is intended as a joke.
However I think it is an innocent comment, and anyone who takes offence at the first comment you made, is probably already thinking the second comment.
(and this is not aimed at MD, this is generic thinking) If the poster had taken offence to the comment, then I would have to think what are they doing posting pictures of their daughter up in that fashion? Surely most undesirables would look at the picture and not make an out-right comment? If the poster was concerned, but wanted CC, then they should have posted components of the picture, a cheek for example to ask whether there is a colour caste.
I think it is a very happy looking young girl. Aren't smiles meant to be a way of showing happiness, and transferring a bit of that to the person viewing them?
Wasn't there a song, 'Thank heavens for little girls'? I wonder whether the PC version of it would be quite as popular!