Fool's gold is actually mainly a payload card. In engines where you can draw deck it is 4$ for 2$ 1buy. If you want some examples wanderingwinder has exemplified this in at least on of his videos.
True, but then it doesn't really deserve to be that much better than Poor House.
Let's make a pros and cons list of going for Fool's Gold over Poor House. Let's start with cons:
* Poor House is ever so slightly cheaper in a way that is almost never meaningful
* Poor House can be Throned/King's Courted
Now pros:
* Doesn't take an Action to play
* Doesn't mind you having other Treasures in hand
* Plays nicely with Stables
* Doesn't take an Action to play
* Has a nifty opener with Nomad Camp
* Is great with Treasure gainers, like Mint and Mine
*
Doesn't take an Action to play