lucy24 - 10:54 pm on Jun 23, 2013 (gmt 0)
Do you have a user-agent whitelist that is absolutely guaranteed to identify all humans? (Excluding the ones who have willfully and intentionally obfuscated their UA. Those don't count :)) False positives-- like the plainclothes bingbot-- are fine. It's the false negatives I'm leery of.
Earlier today while-- stop me if you've heard this one-- looking for something else*, I came across this ancient thread [webmasterworld.com] with particular attention to posts from jdMorgan. On some types of sites you can afford to lock out the occasional human. On others, visitors with elderly browsers-- or security-conscious people who never let their browsers tell the whole truth-- may be a large part of your target audience.