But as you know, less than 3 sm visibility is IMC (except in Class G during
the day at 1200' AGL or less), so VFR flight in those conditions is unsafe
and illegal.

Agreed.

You described being able to see things "down" but not "at a slant" in haze
at 3000'. At that altitude, if you can't see prominent objects 11 degrees
below horizontal, you have less than 3 sm visibility (and if you can't see
prominent objects 35 degrees below horizontal--still nowhere near
"down"--you have less than 1sm visibility).

Any typical day in the Sacramento Valley is going to involve haze,
except for those perfect days. I am certain that I have flown in
conditions of 10, 20+, to almost unlimited visibility, where I couldn't
see Mt. Diable, 90ish miles away, at an altitude that probably put it
at 11 degrees below horizontal.

Standing on the ground at the departure and destination airports, I can
comfortably say that there was 5 sm visibility, as I was amazed at how
different things could look from the ground and in the air. An
un-intentionally omitted fact was that the flight occured around 4:30
p.m., which added another parameter, being the setting sun. The
setting sun and haze could have likely made for poorer visibility, as
I was flying East to West???

Another fact that I will humbly admit to, is that my gauge of distance
probably leaves a lot to be desired. I welcome any and all comments to
how people best gauge distance. I would like to know that when I
report a 5 mile final, it isn't actually a 7 mile final, which I
suspect I might be guilty of.

I'm certainly not trying to be argumentative and appreciate your post,
nor am I looking to get flamed for flying VFR into IMC, which I assure
you, I would not be comfortable doing or be happy about, if I had let
it occur.

Even if you can manage to aviate and navigate without instruments while
flying VFR in IMC, you don't have adequate means to see and avoid anyone
who's legally flying IFR near you. So you're betting their lives that you
won't happen to collide with them.

As I said above, the visibilty on the ground, after arrival, I would
comfortably call 5 miles. Although I'd feel better about stating that,
if I could see a copy of the METAR for that time. Is there any way of
finding METAR information for a previous day??? It would be nice to
see a copy for peace of mind...

I appreciate your motivation for posting, but I think you've overlooked a
far more important lesson than the one you had in mind.

Thanks Gary! Your point is taken! I "did" take a 10 minute flight for
granted, and will no longer depend on a forecast and a pop-up and see
how it feels report for current weather. I will "always" get a
breifing at least one hour prior to departure. The other point in
that, is that there could have been a situation where a temporary TFR
was introduced since the original briefing...

Best Regards,
Todd