It really offends me when people use tricks like this in deliberate attempts to mislead. I see it all the time, especially on the left. Things like an percentage of a percentage or an increase of a rate are key tip-offs of a desire to mislead, as are comparing percentages and numbers, or using rates when the numbers are low or numbers when the percentages are low.
There is an excellent book on the subject that should be taught in all High Schools. The title is "How to Lie with Statistics". It shows many of the techniques that are used to decieve.