My guess is that they will develop heuristics to work out which pages are junk.
You can work out much of these from judicious sniffing of traffic on the network; others you can deduce with some simple heuristics.
heuristics based on estimates of an agent s tactics are drawn from a series of experiments.
Most of them seem to use heuristics or social norms.
Real life problems tend to be tackled by applying suitable heuristics to simplify the problem.