The question was; They're always pointing SW, Does this only work in northeastern North America?

Well, two things. Here in the suburbs of Perth, Western Australia there aren't a lot of Satellite dishes. Possbily only 100 in a 2500 sq km region. Mostly you're only going to find them on places with major telecommunications requirements (and often they have multiple dishes pointing in different directions) or on the odd pub that was convinced to buy "Sky TV" for sports coverage, particularly racing.

There are possibly a larger number of microwave antenna from one of our (failed?) Pay-TV companies, but they all point towards one building in the city. Good if that's where you're headed, not all that helpful otherwise. Also, many were/are mounted *inside* the roof.

You *might* be able to navigate based on outdoor TV aerials, but with stronger signals far fewer of them are visible from the road as they used to be. Also, they'll all be focussed at a particular braodcast antenna in our nearby hills (Perth is quite flat as land goes), so from one end of the metro area to the other they'll change angle almost 90 degrees.

Oh and, from memory, Sky TV satellite dishes here point NE.

Geostationary satellites have to hang over a point on the equator, so in the Northern hemisphere dishes will point South-something, in the Southern hemisphere they'll point North-something, but that's about it. Precise orientation depends on which satellite is the most popular TV relay and where you are in relation to it.

They are a great indication of an area's demographic too; the higher the dish count, the lower the average wage - at least here in the U.K. This is slowly changing, though as cable reaches more people here.
I'm sure the same would work for screen size - there's got to be a phd in there somewhere...

I used to work for Direct TV and they told us that their main transmitter was in Texas, and that there was a geosynchronous satellite which relayed that transmission to all the dishes they served. That would explain why all the dishes in the northeastern US point SW...towards a satellite hovering over Texas. So it depends where you live. I suppose you could navigate knowing where you are in relation to Texas...

Most Sat dishes here in Germany are pointing ca. SSE,
since this is where the Astra satellite hovers.
Good idea, never thought about it!

musashi is right, the DirecTV satellite is in geosynchronous orbit over Texas. (Well, really, it's in orbit over the equator, due south of Texas, I think.) That means from Seattle, where I live, dishes point southwest-ish. However, Dish Network has two satellites, one for each half of the country. They point more south than southwest.