Or perhaps it is simply, as she herself suspects, that as founder and managing director of a company now worth more than pounds 430m, she is Britain's most successful businesswomen. In a male dominated world, she runs her business with a mixture of ideological passion, commitment and commercial flair that is unmistakably feminine. That makes her doubly vulnerable to the favourite British pastime of knocking down erstwhile heroes.
The threatened US research report is just the latest in a long line of attempts to undermine Body Shop's whiter-than-white image. So far, they have been largely unsuccessful: the Roddicks won pounds 276,000 libel damages against a Channel 4 programme criticising their anti-animal-testing stance. Other attacks have so far been similarly deflected.
All that could change with Body Shop's advance in to the US, where environmental awareness is much keener, among both shoppers and investors. That makes it much more likely some mud will stick. Already it may have had some impact, with one ethical fund divesting itself of Body Shop shares.
Will that and should that matter to Body Shop's business? Sales in the British high street did fall after the Channel 4 documentary, but that owed far more to the recession and a formula that is beginning to tire than to the impact of the documentary. Shoppers have also become more and more cynical of extravagant claims on products, so it is possible that many of the Body Shop's customers take its ethics with a pinch of salt.
Far more than other retailers, however, Body Shop is its reputation. Its claims to ethical and environmental purity are an integral part of the product and the company's marketing effort.
If some of these claims are found to be less than truthful that could undermine customers' faith in the whole Body Shop concept - and the effect on sales could be disastrous. For all the hype, Ms Roddick is enough of a businesswoman to recognise the risk. Let's hope she is also enough of a businesswoman to have ensured Body Shop is as clean as she paints it.