Most anything can be made to sound plausible, without any knowledge of space or any of the achievements of NASA one can look to the sky and see that the moon and the stars are also circular in shape, next if I were to stand by the ocean I would see a horizon and watch the sun and moon cross this horizon rather then rise from the ocean. The earth is round and opinions otherwise at this point can be seen as anarchy towards conventional wisdom and science and maybe even common sense.