First, your bags of powders probably don't look like the bags of drugs. Yours are probably designed to be opened and then sealed again, and they are probably not reinforced with a lot of tape, shaped into bricks, etc.
Second, they have on-the-spot tools to test suspicious powders: the swab and the little plastic bag with liquid reagents called a NIK test. The swab is a cloth (possibly pre-dampened with something) that they can rub on your hands, the zippers of your bag, etc and then put in a machine that might beep and say "cocaine" or "explosives" because you had residue on your hands. The little plastic bag they drop in a few grains of the powder, squeeze the bag to break the inner ampoule that holds reagents, and then shake (they hold the top of the bag and flick at the bottom repeatedly) and it changes colour if the powder is a known drug. I believe there are different bags to detect different things, and the agents choose which one to use based on the colour and smell of the powder, as well as the country the bag is coming from.
Almost any episode of Border Security will give you a chance to see these in action. If you are headed to a developed country, they will have this sort of thing and will be able to establish what your powders are very quickly. And of course they don't search every bag: sniffer dogs, xrays, and the like lead them to the bags that need to be looked at. Your protein powders won't smell like drugs and they might not look like drugs on an xray.
If you are headed to a country that you think might not have budget for all the whiz-bang tech, or where officers might be corrupt and use the opportunity of your powders to shake you down, then that's different. Should that be the case, you'll have to balance the possibility of trouble at the airport against not getting your protein during the trip.