Sgt_Kickaxe - 6:51 pm on Nov 26, 2012 (gmt 0)
No human test needed since I only want to be sure the referring url belongs to my site. e.g. They clicked the link on my site and not on another domain.
Since Googlebot does both apparently it sometimes gets a blank page and sometimes passes to the destination. Is this a dangerous thing? If it's not I'll go with option #2 and stop showing blank pages, I'll redirect fails to a single blank url instead.
I'm not sure Google spam doesn't make a distinction between being shown a blank page and being redirected to one.