Without knowing if that's the case, these metrics are definitely easy to manipulate. For example in calculating purchasing power parity, the "basket" of items you choose can significantly misrepresent the common, basic needs of people in poor countries. And it should be remembered that the World Bank's global poverty line is only 1.90$ a day.

Based on my own experience of living in a poor neighborhood in a very poor country for a long time now, I am always skeptical of these claims for reasons that would be too long to list out. Inflation and increases in the cost of food and rent here have far outpaced the World Bank metrics ($1.25 in 2005, $1.90 as of 2015) and the incomes of the average person (~$100-150 a month).