Lemond got a suspicious injection once in the 1989 Giro d'Italia...so his team may have been doping him without his knowledge if one wants to hold him on a pedestal.

Lemond was beating a lot of superstars in the 1980s that were blood doping (Hinault was probably blood doping - that's where you freeze your blood in the offseason or between races and then superinfuse yourself for "big days" - it went to the wayside because EPO was so much more effective and convenient) which is suspicious as well.

Lemond was also not exactly the best trainer compared to people like Lance Armstrong. He was teased by magazines for starting some TdFs overweight with a slight potbelly.

Doping in cycling, heck doping in all sports has been around a long long time, well before Lemond. Stimulants and a wide array of other drugs have been used in top sports for a long time. So it gets very suspicious whenever someone is beating the top end performers at any point in the last 50 years.

That said, I think he was pretty clean, or at least cleaner than the EPO guys that knocked him from the peloton.