I don't know about cheaters/frauds, although i'm sure they are out there.
If WGT was designed to mimic real life golf, then the scores would be close to those of real PGA Tour golfers. Scores for good WGT players would be in the 60s and 70s. Those are real life scores. How many 58s or 59s have there ever been on the PGA Tour? Darn few. Totally unrealistic scores.
On the other hand, if WGT was designed to be just another video game, then sure, one can play it enough and get so good at it (like most any video game) that consistent scores in the 50's are possible.
I'm not the best WGT player here, and I'm not the worst, either. I will say that it is a bit discouraging to see all these scores in the 50s, because I know I don't stand a chance playing in a tourney against those players. But is what it is; I enjoy this game, I play for fun, and I don't try to make this like so many video games where one tries to achieve the highest score possible (or in this case, the lowest score).