A lot depends on what your subject is about.
Unlike YPN, Google had studied the map of the world and found out that people do live outside the US. They have also cottoned onto the the fact that people outise the US lead prosperous lives, and buy products from adwords advertisers. The adsense view is a global one, and they don't knock foreign visitors clicks down simply because they aren't unfortunate enough to live in the US.
Google are looking for how clicks convert. If Google devalues a click it will be because they don't feel it's going to convert for the advertiser for some reason or other.
If your site is about something of interest only to US visitors, and all the ads are targeted at the site from US advertisers, then it's likely that clicks from the rest of the world may not convert, so therefore it's sensible to smart price them.
However, if your topic is more general and likely to be of interest to a wider audience then clicks made outside the US may well have equal or better than clicks from US visitors. On my site, I find that the UK viewed page shows mostly UK ads, and the page viewed in the US shows US ads. As far as I can tell, both pay equally well.
If your site is getting low value clicks, then the reason is that Google feels the ads don't convert for advertisers, or they are showing only low value ads on your pages.
It might be an idea to browse a couple of threads in the forum library that discuss low paying clicks and smart pricing.