I wonder if something is getting messed with upon transmission. I assume both printers work ok on the same PDFs if plugged directly into the computer?
In my experience, a lot of PDFs can be in some way funky such that, when the rendering engine on a printer attempts to render it, it chokes the printer in some way. This only applies to laser printers (inkjets rely on the OS to do the rendering, at least as far as I know). I've seen symptoms ranging from funky-looking output to crashing the printer--needs to be turned off and back on to get it to recover.
That'd explain why printing a TIFF would work, since that's just a bitmap instead of a PDF that needs to be rendered; you can also use the Advanced box to tell Acrobat/Reader to "print as image", which has the same effect without the extra step.
Only question is why this is happening with an Airport-connected printer; I wonder if in some way it's having trouble feeding data, at least from certain PDFs, to the printer? Maybe it's what's choking on the funky PDFs?
If so, not much you can do, since that'd be a hardware issue.