The spotlight was turned on England at the weekend with reports that Harlequins' internal inquiry had heard allegations of cheating at all levels of the professional game.
But Johnson (pictured) believes the practice of faking blood injuries - whether by use of a capsule, deliberate cutting or re-opening old wounds - is not endemic in the game.
He told Radio Five Live: "I don't think it is widespread. It is certainly not widespread in my experience as a player and with the England team this year managing it."
He added: "Have things like that happened before? I think you would be naive to say they haven't. Is it widespread? No, I don't think it is.
"In my time playing, including the time under Dean (Richards) and all my time playing with England, I never saw or heard about a blood capsule.
"I never thought blood on the field was anything other than blood. Personally, I have never had it done and I have never come off for anything but genuine blood. I don't think it is widespread. In saying that, it has happened at Harlequins."
Johnson was saddened that Richards, his former team-mate and coach, had been caught up in the scandal and paid for it with his job and a three-year ban.
"Dean took a desperate gamble in that situation and it is clearly wrong. It is a sorry tale and he has paid a very heavy price for it," said Johnson.
"I am particularly sad about it because Dean is probably the biggest name in Leicester Tigers history. He had a great record here as a player and a manager and he was doing a great job at Harlequins.
"It takes away all the good things they have done on and off the field. He has taken them from the first division into Europe and winning away in Paris. Those good things are lost a bit now."