Catfish have presumably been active on GAG right from the start, and a lot of people tend to accept them as a fact of life here. You get better at spotting them over time, but this Take isn't about how to spot them, it's more about why they are undesirable, generally.
Catfish: someone who pretends to be someone they are not online to create false identities, particularly to pursue deceptive online romances.
Why do I think they're a problem? There are a number of reasons.
1. They mislead people as to what kinds of behavior are normal.
For example, the nymphomaniac catfish, who actively encourages real girls to do casual sexual acts they may not be comfortable with - because everybody else is supposedly doing them.
2. They present a jaundiced view of western society.
This is not only incorrect to start with, but also encourages non-westerners to hold western people in contempt, western values in contempt and western culture in contempt. For example, the legions of non-western guys who come onto the site to use it as a dating agency, because western women are THAT easy. Apparently.
3. Catfish 'breed' more catfish.
Hadn't actually thought about this one until the other day, but other posters pointed out
a) Women pretend to be men, on occasion, to avoid hassle from guys who believe that the behavior which catfish display is 'real'. An easy way of avoiding said hassle is to become just another 'guy'.
b) Men pretend to be women, to get real women to talk to them (in the belief that women won't talk to men, because the women have had previous bad experience with guys who believe that catfish nympho behavior is real.
So, ignore them if you will, troll them if you want, but don't kid yourself that they're harmless...