As scarce as hen's teeth - You might have noticed that birds do not have teeth but they have beaks. Now if you sit down to discover the teeth of a hen, it is really impossible to find one, because it does not have teeth. This idiom, namely ‘scarce as hen's teeth' refers something which is rare and you would not be able to find it so easily or maybe it is impossible to find it even.
1. There are no keyboards in this shop; keyboards look to be as scarce as hen's teeth.
2. Well, I am not able to feed myself and I am so hungry because hotels seem to be as scarce as hen's teeth in this area.
3. I wanted to buy a dress but no boutique here; they are as scarce as hen's teeth.