These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fair for Its Day: To modern audiences, Salgari is a moderate racist and sexist. When the novels were written (between 1883 and 1911), Salgari was a radical proponent of equality between genders and races.
What an Idiot: In The King of the Sea the Sultan of Shemmerindan had ordered the American-built (more specifically in Oregon) ironclad warship Nebraska to avenge his father, killed by the Dutch years earlier, and paid a good chunk of the price in advance. When the Americans showed up with the ship they discovered that the Sultan had been assassinated, and his successor told them to keep the advance money and a ship that could have given him power over the whole Indian Ocean. Upon discovering this Yanez lampshaded his stupidity, and promptly asked what the Americans wanted to sell him the ship.