Why didn't anybody recognize the Z fighters at the Cell games? During the Cell-games saga, Mr. Satan was supposed to be the World Martial Arts champion and he was held in high regard by most common people.

By contrast the Z-fighters, most of whom just happened to be high profile fighters from the 21st through the 23rd World Martial Arts tournaments, were perceived to be nobodies by the general populace.  

But they were all the top contestants of the previous Martial arts tournament, which can't be too much more than 15 years before the Cell games.  

They were the highest profile Martial artists of the previous decade.

If we compared this to modern boxing, it would be analogous to praising Wladimir Klitschko, but completely dismissing Mike Tyson and Evander Holyfiled.(although Klitschko is younger).

I can understand why they didn't recognize Goku, but Piccolo, Tien, Yamcha, and Krillin should have been immediately recognizable.

Why were they dismissed so much?
Common people in DBZ don't generally outright celebrate people unless they are constantly bombarded in the mainstream media. Like Mr. Satan for example. He was always on television and groomed to be a hero by himself and his cohorts. He used his money from winning the tournament (no Z warriors participated) as machinery for his hype. The Z warriors don't have such interest.