Firstly, with anything carp fishing, you have to remember that the vast majority of practices in carp fishing have not come from scientists but from Joe Public. These practices would not pass any sort of scientific testing procedure, They are all purely circumstantial. The only ‘scientists’ I know writing about carp fishing are Simon Scott and Dr Bruno Broughton - that said I do have a degree that has some relatable areas to carp fishing. Secondly, the carp is very forgiving in how we approach catching them, which is why we have so many ways of doing it. No matter what you are doing, you have a bait, on a hair or side hooked, with a hook, tied to some line, with a weight / float on some more line connected to a rod and reel. All the rest of it is pretty much irrelevant - just fishing in weed requires a bit more thought. For every story of a rig or bait change that turned a season around there are 100s if not 1000s where the same change made no difference, and may even have made it worse.
I’ll start with the only good reason to pre-soak your baits in lake water. That is to slightly soften them and to get the lake bacteria acting on the bait to start giving off its attractors. I’m talking when you get to your swim to start soaking and give them 30-60 minutes while you set up. The longer you leave the baits soaking the more attractors you will lose. Basic chemistry/physics drives high concentration items to low concentration areas - this is known as a concentration gradient. The biggest shift is water going in to the bait, but as water goes in something starts to come out - your attractors. The longer you soak, the longer the water and bacteria act to release the baits attractors so you are lowering the attractiveness of the bait. Soaking in a liquid food is a much better option if you can afford it.
So washed out baits are supposed to appear less dangerous because they give the appearance of a bait that’s been in the lake for a few days and so the carp will perceive these as safer - WHY? Why is it safer? If they were scared on day 1 of a baits’ presence, they’ll be scared of its presence forever. Washed out bait is still a freshly introduced bait - just one with reduced attraction and possibly colour. However, you have not given the carp a point of reference for it to judge your washed out baits against. Not that it can even think like this. You’re relying on the point of reference being that the carp possibly sees more ‘old’ bait on the lake bed than fresh out the bag full colour baits. That old bait may well be paler in colour, so your washed out baits match this more closely - I get the idea - it's just fundamentily flawed . So you now have a situation where you’ve paid for a bait full of attractors and you then soak them to wash them out and reduce the attractors. Does that not seem a waste of money? Now, would you buy a pale bait made with low levels of attractors in it? Even if it was cheaper? Not if you have half a brain cell. We know for certain that carp predominantly find food through dissolved chemicals - we don’t know how much they use their eyesight to locate food. Why would you fish against other anglers using ‘full strength’ baits while you hedge your bets on baits with lowered attraction and the carp using its eyesight to locate your washed out baits?
Personally I don’t think carp feed by sight very much at all - they don’t need to. They use their sight far more for predator detection. Think about what a carp eats naturally - it can’t see much of it - so why would it use its eyes for feeding at all? It certainly can’t see what it’s putting in its mouth. Many underwater videos show carp homing in on a pop up, the misconception is that it’s seen or sees that bait when in reality it is just tracking the chemical trail off of it. Carp are able to follow dissolved chemical trails like a road. They could be blind and still act in exactly the same way when approaching a food source such is their ability to locate food purely by the concentration of dissolved chemicals. Why would a carp even associated colours with food at all?
So please, let’s stop this washed out nonsense once and for all.