You may find that you have to wrap the code that gets called when Ajax fires in something to catch the user agent. I.e. if your making an Ajax request to a php script in order to return data, you could wrap that php code in something like this (please excuse the Sudo code):
if(in_array($_SERVER['HTTP_USER_AGENT'], $knownagents){
//known webspider, or blocked agent, return nothing.
return "";
} else {
//not a known spider so continue.
}
?>
Thats very generalised but you get the idea. I put a short list together in JSON format a while back, you can find it here if its of any use: https://www.source-control.co.uk/knownspiders/spiders.php
PM me if you need any more specific help than that with development, hopefully someone else will have a slightly easier way of dealing with this though heh
