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

cheers to the scotch drinkers.....sounds yummy. I haven't strayed far from Jack Daniels and then only on occasion, and if I had to choose 
would go with the smokiness of smoke itself when listening to music
or the birds in the yard......can't afford the good stuff out here on the east coast, but it's all good out west.....contemplated a move to Portland after a summer vacation stop into my first legal shop there.
My oh my what nicely trimmed buds and so affordable.......
     For me the green does wonders for the senses....aural,visual etc.

Yes, absolutely - I have this experience often. Haven't read through all these responses yet, so maybe someone already said this, but one factor you might not be taking into consideration are the fluctuations of your actual ears. According to an audiologist I once saw (I was a drummer subjected to loud noises regularly, and needed to have custom earplugs made), there are muscles in your ear that expand and contract to protect your inner ear from loud noise. I would guess if you were tense, or your ears were tensed, you might be essentially muffling your inner ear somewhat, or preventing it from being receptive to the sound coming in. Maybe in the morning you are relaxed and in the night you are worried. Or some variation of that. Sounds hokey, but I always consider this. 

Keep a log. That way you have some chance, albeit a small one, of correlating what you hear from day to day, week to week, month to month to something, anything. Moving this, changing that, replacing that, time of day, whatever. Unfortunately, and I say this with the utmost sincerity, you won’t be able to correlate the sound to things you don’t know about or things that are not usually thought to have any influence whatsoever on the sound, that you would never suspect.

Made the scene
Week to week
Day to day
Hour to hour
The gate is straight
Deep and wide
Break on through to the other side
Break on through to the other side

Okay, this is ridiculous!
Notwithstanding all that has been written here, today my system is sounding like it NEVER sounded before.  All the parameters of sound are way better.
Is it electrical? Who the f@#$ knows?!

Its enough to drive you totally insane.