Making wild claims that cannot be substantiated are nothing new to the extreme right wing in the Republican Party. It is part of their DNA you use hatred to motivate people. This hatred relies on the dehumanizing of a group in the minds of a targeted audience. Some people are easy to dehumanize. Child molesters, terrorists and war criminals who kill civilians come to mind. But, the process of making claims to instill hatred follows a pattern.
In 2001, some incoming Bush administrative staffers circulated a joke about outgoing Clinton staffers removing the W's from all their keyboards. This may have happened in one or two cases. But, that got lost in the hysteria that followed. Stories of widespread vandalism by outgoing staff spread like wildfire. The people responsible for government property, GSA, investigated and reported ", "the condition of the real property was consistent with what we would expect to encounter when tenants vacate office space after an extended occupancy."
But, Republicans in Congress weren't buying the excuses made by career bureaucrats. They had their own career bureaucrats investigate. The GAO did so, and they reported, they "had found no damage to the offices of the White House's East or West Wings or EOB" and that Bush's own representatives had reported "there is no record of damage that may have been deliberately caused by the employees of the Clinton administration."
None-the-less, Bush's Press Secretary, Ari Fleischer promised a full investigation would be completed and a report would be issued. We are still waiting for that report. In spite of multiple investigations and all the facts, hatred of Bill Clinton gave this rumor legs in the right wing story mill. There are people today who refuse to believe it is not true. It is easy to see why they hysteria about Mass executions by the Taliban would gain traction today with the same audience. Hatred is a strong motivator. It has kept the extreme right wing of the Republican Party relevant for decades.