To distribute dust you can use a flour sifter ( the type with a pull trigger that is used in dusting a cake in icing sugar.) and count how many times you pull the trigger. This allows you to pull the trigger and release to evenly cover the rug. 50 grams of dirt is about right for a 4x4 foot rug. In a home you usually encounter dust, grit, fluff and larger debris. Dust and grit is replicated by a mix of equal parts flour, baking soda and fine sand. Fluff is replicated by kpok, which is spread by holding a large clump and holding it about a centimetre above the carpet and letting it stick how it wishes. larger debris can be replicated by holding about 100 grams of clean cat litter in your hand and holding MOST but NOT all and throwing it randomly over the rug. I haven't measured how fast I move the vacuum across the rug. You could take the size of the rug and time how long it takes to do 100 passes figure that out and then calculate the average speed based on that. I vacuum in a w being straight forward diagonal back and repeat. Overlapping 50% is my standard. If I understand your second to last point correctly, science and theory has no effect on a practical test other than the hypotheses. This is why we test, to avoid unknowns and practically prove them correct or incorrect. To account for particle sticking etc you simply weigh the whole machine before and after. weighing the carpet proves what goes in and out. Hence the record keeping. The important properties of the carpet are as follows: two pile, This is tricky for vacuums as there is a loose tall pile of handle then also a very denso short pile bellow. This makes cleaning extremely difficult. Wool loop pile, wool loop pile carpet is great for creating traps and block as it is very densely made. Dust in the centre of a loop is difficult to clean!. ZSolution dyed nylon is great to represent a typical average carpet. Mohawk carpet is great for representing thedeeper piles that trap dirt. an area the size of a bottle cap can hold up to roughly 2-3 teaspoons of dust without looking terrible. Hence it is terrible to fully clean and know it is clean.