A stamp sold to a collector represents a profit for the relevant postal authority because it is not being used to pay for the delivery of mail. Some countries were quick to realise this and began producing special issues with the sole intent of generating revenue – in San Marino, for example, stamps provide a significant portion of the country's revenue. Such were the numbers produced that sometime in the 1960s or '70s the stamp dealer Stanley Gibbons took the decision to exclude the excessively prolific countries from their catalogues. Despite this, most countries now produce many special issues a year so it is no longer feasible to produce a single, definitive, list of the World's stamps. It is under these conditions that a trade in counterfeit stamps began to flourish.
Due to the shear numbers available, it is no longer possible to collect all the World's stamps so philatelists have, instead, started to specialise on particular themes. This may be anything that interests the collector varying from, say, a particular country/continent, to sporting events, types of animals or anything else imaginable. With this in mind the counterfeiters print fake stamps covering any populist subject you can think of, some of them so trivial that it is hard to believe any postal authority would seriously consider them for a stamp issue. The hallmark of these stamps is that they are invariably for a small, unfamiliar country, often with a non-latin alphabet that, in the absence of any definitive list or catalogue, the collector would be unable check the provenance of. Additionally there would be lots of expensive extras: typically mini-sheets with ornate backgrounds and high value stamps together with features that make them more attractive. Indeed, the situation with fake stamps has got to the stage that many affected postal authorities have issued statements to the effect that mail bearing those stamps will not be accepted!
In light of the above it is no surprise that there are many stamps showing Boris', and Julie's, artwork – they are both so prolific that there are plenty of images available for use. I have therefore taken the decision to exclude all stamps from the Borisography on the following grounds: