The 48-year-old retired American sprinter, one of athletics' all-time top performers, said he did not know where the sport was headed and that the main focus should be on restoring athletics' credibility.
"Nothing that happens in Rio with athletics is going to snap back the credibility in the sport," Johnson, the only man to win the 200 and 400 metres gold medals at the same Olympics, said in a telephone interview.
"That is going to take some time and there has to be a consistent and ongoing effort to reestablish credibility.
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"I never expected this and never would have imagined that things would have been revealed to be this bad."
Widespread doping problems, allegations of bribery to top athletics officials and a drop in both spectators and sponsorships are among key issues currently plaguing the sport.
Johnson spoke while launching a new charity to assist young men and women in developing athletic and leadership skills that can be used in their troubled communities globally.
Reaching out to youth is just one area where athletics must put an emphasis on, Johnson said.
Last year an independent commission for the World Anti-Doping Agency revealed widespread, state-sponsored doping in Russia. The commission released a second report in January that accused the International Association of Athletics Federation of having "embedded corruption" at the very top of the organisation under former president Lamine Diack.
"Before all of this scandal broke ... athletics was already in trouble and had been on a downward spiral for many years in terms of popularity, in terms of sponsorship, in terms of professionalism of the sport and the doping issues as well," said the straight-talking Texan.
"It's been a big problem for many years that young kids growing up, that not only are they not inspired to participate in athletics because maybe you can't trust what you are seeing ... but they may think you have to be doping to be in that sport."
According to Johnson, athletics must become truly professional. A $20,000 grant because someone is in the top 10 in the world in their event is not the answer, said Johnson.
The sport's biggest star, Jamaican sprinter Usain Bolt, for example, ranked only 73rd on Forbes magazine's list of the highest-paid athletes for 2015.
"(Athletics) has got lots of problems that need to be addressed, but I think the mistake would be for leaders of the sport to focus on those things because those are easier to talk about and easier to deal with than the scandals and the credibility issues," Johnson said.
"You have to continue to let fans and potential new fans know that we understand the problem that we have with this sport from a credibility standpoint and we are not ignoring it. We are dealing with it."
Long an advocate of tougher sanctions for dopers, including missing an Olympics, Johnson said educating athletes on the ill effects of doping is important. He also feels governing bodies must work uniformly in handling doping cases.
"The local federation is saying one thing and then the global federation is saying something else, the IOC (International Olympic Committee) is saying something else," he said.
"You have got to have a consistent process that is an expedited process that does not stretch out over 18 months."
And above all, there must be transparency in the sport.
"For a long time we thought certain things, only to find that we were being lied to," Johnson said.
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