Here's my list of people who shouldn't be in the Hall of Fame but are, people who were never #1 and won only one GS title or none (pure double players like Frew McMillan and Natasha Zvereva are excepted from this list):
Mal Anderson
Rosie Casals
Michael Chang
Owen Davidson
Sven Davidson
Francois Durr
Andres Gimeno
Frank Hunter
Yannick Noah
Gabriella Sabatini
Pam Shriver
Michael Stich