I remember this topic came up a long time back (maybe 2005 or so) and the discussion brought up “soundscans” which are apparently how they measure such sales. Soundscans are tracked when the UPC is scanned for sale.
At the time, “Houses” (to be fair it had been on market less than all the others) had moved about 25,000 units.
The Land of Rape and Honey (1988): 323,370
The Mind is a Terrible Thing to Taste (1989): 487,474
In Case You Didn’t Feel Like Showing Up (1990): 196,225
Jesus Built My Hotrod (1991): 148,894.
Psalm 69 (1992): 961,952.
The Fall (1995): 30,196.
Filth Pig (1996): 236,557.
Dark Side of the Spoon (1999): 79,459.
Greatest Fits (2001): 89,283.
Animositisomina (2003): 46,319.
Houses of the Molé (2004): 45,419.
Rio Grande Blood (2006): 34,346.
The Last Sucker (2007): 5,140
I can’t see exactly how up to date these figures are (the Last Sucker seems to be from '07, which explains that figure… or does it?)
If these figures are up to about '07, I’d say the Bush albums have sold more than the older ones since then, mainly because the Warner Bros. albums were (still are?) out of print.
There’s also the issue of digital sales which I guess is not incorporated in these figures.
These numbers are from 2007 - I imagine TLS has sold more than 5000 copies in the intervening 4 years. And also, the Bush albums are post-downloading. So if you take iTunes and mp3.amazon and emusic and all that into account, Al may actually be right if you go Bush albums vs. later Paul albums.
In the end, it doesn’t really matter that much. Only Gene Simmons types believe sales = quality.