Professional sports are full of dopers. This is not an opinion. Professional sports have been full of dopers for quite a while. This is also not an opinion.
Fans like it because it makes most sports more interesting and allows occasional mass-judgment and public crucifiction. That is an opinion.
More: The Doping Crisis and Youth Development
There are few, if any, sports untouched by the current wave of indignation pointed at athletes suspected, accused, and/or convicted of using performance-enhancing drugs. From HGH to epo to good old-fashioned steroids, science forever races towards new ways to improve human performance beyond its natural boundaries.
As science comes up with new ways to go faster, higher and stronger, athletes find ways to get their hands on these laboratory step ups, and in turn, fans demand and commissioners seek new methods to test for "Lance's Little Helpers."
Understanding why doping makes fans so angry is key to fixing the problem. It makes fans angry because it feels dishonest. It's a misrepresentation of who you claim to be and what you claim to be able to do.
Fans want superstars performing extra-human feats of strength and agility. But they have to be doing it clean.
Fans want to know that this person is different because of their special mix of genetics and drive, not because of their special mix of hormones and injection sites.
More: Liars, Cheaters and Thieves in Your Sport: Part I
Sports are entertainment and fans demand to be entertained, but within the fan's definition of fair play.
When it comes to light an athlete doped, they are forever branded a cheater. Not only did they cheat their opponents out of wins, but they cheated the fans out of purity. They betrayed the one-way trust that fans feel athletes should feel.
Athletes, though, know keeping their paycheck steady and Q score up depends on doing their job better than anyone else. That's a lot of pressure.
More: Liars, Cheaters and Thieves in Your Sport: Part II
They probably see other athletes doing everything they can to stay ahead. And why not?
The name of the game is to go faster, to hit harder. The leap from external equipment improvements to internal are very small, and make sense.
There's a saying in cycling that goes, "It's not the bike, it's the engine." Meaning your fitness level matters more than anything else. You can race on any bike with two wheels. Assuming you could hang with the peloton, you could show up on a fixie painted purple and no one would say anything.
You would also get destroyed, lose your sponsor, and starve. You should have brought the super-expensive piece of gear if you actually wanted to compete and win. All the training in the world won't make up for bad tools when the margin of error is fractions of a second.
More: No Need to Cheat