As anybody who's ever tried to train an email spam filter from scratch can tell you , the number of messages you need to classify in order to be useful is huge.

As anybody who's ever tried to train an email spam filter from scratch can tell you , the number of messages you need to classify in order to be useful is huge. With email spam, everyone can more or less agree on what it looks like so you can reuse other people's training data but by deciding on what is a "bad" online dating message is much more complicated.