A short note: the froth itself is not something having a negative impact. The source determines if it is of any use or useless. i.e. If it comes from churning the cream or yogurt, it is surely a good one will turn in to butter even the leftover (buttermilk) is useful, if the source is from some chemical or some waste, it surely is poisonous, the froth and the residue.
Our thoughts have to be really vital if we are looking for purity around us. Throwing negative thought towards others eventually leads to damage for all!