lucy24 - 2:26 am on Jun 2, 2013 (gmt 0)
not to filter them by IP range because of frequent changes
I remember that line. But they really ought to know better. Claiming to be a major search engine is one of the simplest robot tricks; how many fake googlebots do you meet in the course of an average day?
I don't see a lot of fake yandexbots. Fake yandex searches, yes. Luckily they are very easy to distinguish from the real ones.