The problem with Manuka honey is that A) it is expensive, B) more often than not it actually contains very little Manuka C) it is so messy to use.
Although this has not reported on Manuka honey in the US I have no doubt any testing would come to the same conclusion.
As a result of the high premium paid for mānuka honey, an increasing number of products now labelled as such worldwide are counterfeit or adulterated. According to research by UMFHA, the main trade association of New Zealand mānuka honey producers, whereas 1,700 tons of mānuka honey are made there annually representing almost all the world's production, some 10,000 tons of produce is being sold internationally as mānuka honey, including 1,800 tons in the UK. In governmental agency tests in the UK between 2011 and 2013, a majority of mānuka-labelled honeys sampled lacked the non-peroxide anti-microbial activity of mānuka honey. Likewise, of 73 samples tested by UMFHA in Britain, China and Singapore in 2012-13, 43 tested negative. Separate UMFHA tests in Hong Kong found that 14 out of 56 mānuka honeys sampled had been adulterated with syrup. In 2013, the UK Food Standards Agency asked trading standards authorities to alert mānuka honey vendors to the need for legal compliance. There is a confusing range of systems for rating the strength of mānuka honeys. In one UK chain in 2013, two products were labelled "12+ active" and "30+ total activity" respectively for "naturally occurring peroxide activity" and another "active 12+" in strength for "total phenol activity", yet none of the three was labelled for the strength of the non-peroxide antimicrobial activity specific to mānuka honey.