Overwhelming. Infuriating. Demoralising. Words that capture the reaction of many South Africans to politics, but also accurate descriptions for how anyone following sports must feel after yet another doping allegation surfaced over the weekend. This week, it's the turn of the UK, and a doctor Sunday Times journalists reportedly caught on camera prescribing a full range of illegal drugs to an athlete, as well as boasting of 150 top sportsmen whom he has supplied with banned drugs.Last week it was Russia. Or China. Or Spain. Or was it Turkey?I lost track. In March it was Kenya. Perhaps May will be for Jamaica, or maybe we'll revisit Russia, this time for swimming. Or it will be an entire sport, rather than a country. Rugby? Football? The carousel never seems to stop spinning.If anything, it's gaining speed, because scepticism gives birth to more questions, and the answers to those questions are rarely favourable.They simply add to the initial scepticism, driving more interrogation, and on and on we go.So it's down the rabbit hole we fall, further and further into having no idea whether what we watch on our televisions every weekend is believable as a clean contest.The latest allegations from the UK offer some enlightenment into the problems anti-doping faces.The doctor, Mark Bonar, is a self-described anti-ageing expert, working in an exclusive clinic in London.He is, to be blunt, a dodgy doctor with a questionable ethical record - he is currently facing an inquiry for keeping a patient in the dark about having terminal cancer, allegedly so that he could keep providing expensive alternative treatments to her.He has a history of unethical behaviour and a reputation as untrustworthy. So when he makes allegations about doping, he's easy to dismiss as a liar, a sleaze.I would not be so quick on that dismissal - I'd suggest that an unethical liar and sleaze is exactly the kind of person who'd dispense illegal drugs to athletes for the right price.So his personality makes him more likely to cheat and dope, but also more likely to lie. Where does that leave us? In my opinion, rather than the "Much ado about nothing, this fool can't be believed" dismissals that are doing the rounds, he should be taken very seriously.On the other hand, he can't be blindly believed without proper investigation - his history warns us against that.But this polarisation of responses to his claims has already happened, and it means that what should be a discussion becomes an argument, and the truth is left sitting lonely in the middle.The reality is that only thorough investigation will reveal either that he is lying (case closed), or it will confirm that his boasts are the truth, and you're closer to catching 150 cheats.If 150 is an exaggeration, so what? Twenty is enough - this doctor may be the canary in the coal mine, and anti-doping would be one step closer to cleaning sport.The problem is, who does the investigation? The Sunday Times report did not just implicate the doctor (and 150 as yet unnamed athletes). It also claims that UK Anti-Doping knew the allegations two years ago, but after a cursory investigation, decided that there was little or nothing to the claims, and the matter ended there.Parliamentarians have demanded resignations and suspensions of those involved, and what will be most interesting is to see how this aspect of the story unfolds. UK Anti-Doping, for its part, was quick to point out that its powers of investigation only extend to doctors who are governed by sport. In other words, this doctor, at his anti-aging clinic, is out of their reach.That is an extraordinary, and depressing, legislative handcuff, if true. Other anti-doping agencies have investigated and banned doctors, but UK Anti-Doping can't?It means that the authority responsible for protecting the athletes' rights can't investigate in probably 99% of cases where doping happens.Ultimately, this is the most damaging thing to emerge from the latest turn of the doping carousel. Athletes and fans could look at this, and quite rightly ask, "If not you, as the organisation whose mandate is to ensure clean sport, then who?"Who indeed?..