Respect from me for corner case when beggar/poorhouse is better than beggar/garden
You got Beggar from your opponent's Swindler, Poor House is the best engine payload on the board and the engine is stronger than Beggar+Gardens.
Seriously? That sounds an awful lot like "Scout/Chancellor is a great combo - if all other cards on the board are Embargoed five times and you got them both from Swindler."
I mean, come on. Swindled cards that aren't even used as part of a "combo"?
It's a lot better to get an Estate Swindled into a Beggar and then just build a regular engine than to also get your Worker's Villages Swindled into Gardens if you're going for the engine.
That's like saying that sometimes Curse/Gardens was better than Gardens/Worker's Village, because if Swindler had hit my Gardens and replaced it with a Worker's Village i would have less points.
Technically true, but i feel you are interpreting the question too much as "Can you make up a case where i would want to gain a Beggar instead of a Gardens if i allready bought Poor House?" instead of "Are there boards where Beggar/Poor House is a superior strategy to Beggar/Gardens?"