Have you ever hated the sound of your system one day, and loved it the next?

I have never felt there were changes from one moment to the next. I have had first Quad els57s and later Quad 2805 speakers, and they have always sounded the same from one day to the next. The 2805s were an improvement, but in the same family. After a while with the 2805s I decided I needed a more powerful amplifier than the Quad 303, so I acquired a refurbished Quad 606-2, and that was indeed better, but every single day, and not varying from one day to the next.
I do agree with Shadorne that buying gear that professionals also use is a good way to proceed. Tony Faulkner, the famous classical sound engineer, also uses Quad stats for his recordings. My small system uses Harbeth P3ESRs. The British Library’s sound archive uses Harbeth speakers for their recording and transcription work. Neither of them go for audiophile tweaks. They know better.

@shadorne , I don't think those are the tricks @clearthink was asking about...

This is probably the single biggest reason audiofools hear amazing things from fuses or ordinary bits of wire.

+1

However, an even bigger reason audiofools hear amazing things from fuses or ordinary bits of wire is that they wind up "reversing" them.

shadorne "A simple trick is to buy the same gear that is used by professionals"
Yes every hobby has amateurs who do this they think "if only I had the same set of clubs as Tiger Woods" or "if only I had the same piano as Vladamir Horowitz" but of course it doesn't work that way and in the case of audio and Music Reproduction Systems I prefer not to let others' do they're thinking for me.

Much of what many have said here is true. To go to extremes, whether love or hate, is to miss the glorious middle of true enjoyment. 

Mea culpa!