'idiot smile' vs. 'idiotic smile', idiomaticity and usage

Question

I observed that 'idiot' is sometimes used as a modifier, which, as grammar.ccc says, 'are like teenagers: they fall in love with whatever they're next to. Make sure they're next to something they ought to modify!'

Some instances of real English usage I found, among others, are the following:

What kind of idiot teenager agrees to baby-sit on a millennial New Year's Eve, anyhow?

They tried a plastic slide, but some idiot teenager broke it. Wood? It splinters as it ages.

Other than those there are a lot of other example, especially in reference to children, boys and girls.

So, I would like to know whether the English language has some limit in using 'idiot' as a modifier outside those cases.

I ask because I want to say that a friend of mine has an 'idiot smile', but after searching a bit I didn't find a lot of occurence of that expression and it seems that 'idiotic smile' is preferred.

Answer 1

It's a fair question, and I don't think there's an easy answer. You must probably check for usage amongst friends and colleagues, on Google, and in a collocations dictionary. This is true for all 'attributive nouns': why a 'football manager' but rarely a 'badminton manager'? (probably because there aren't that many).

I remember the example in the Family d'Alembert series: The Primary Computer Complex relayed instructions to the myriads of idiot versions of itself in preparation for the final battle against humanity (not an accurate quote, but you get the picture). 'Idiotic' just wouldn't work here. I think 'idiot' focuses more on the agent or sub-agent (drone computers) being referenced, 'idiotic' on the behaviour. So, idiot teenager but idiotic smile / plan / decision / comment.