>>1
This is a pretty old technique. They obviously don't work if you're aware of them, and any human making a spambot for any particular site would be. I guess the idea is that there are certain entities, who write bots which scour the web for orphases to vomit and shit into on contact. Alternatively and perhaps more likely one could imagine children running generalized orphases filler even if they themselves were not capable of creating a trivial spam bot (or even configuring one properly). In theory most adults don't suffer from this sort of degeneracy, so you need only have a basic test to weed out the children and the most perverse of the deviants to have a spam filter that often works.