btherl - 12:57 am on Jul 19, 2012 (gmt 0)
Thanks for the feedback everyone :) lucy24 are you talking about multiple spaces? Yes that does sound suspicious..
The reason I'm avoiding whitelisting is mobile user agents - there seems to be a lot of them. We may end up doing it though.. there's a lot of PHP libraries available that identify mobile UAs and we could use those.
I definitely want to avoid explicit blacklisting, because they multiply every day.