Ok. Quite a bit of back and forth, here, so I'll recap and update.
Maybe I should have given more details in the original post.

It was purchased at Wal-Mart and I did not read the label when I
bought it... it was the Green product, by Klean Strip.

However, I would still expect it to be and perform as, otherwise,
normal (for me) mineral spirits, green or not. It shouldn't matter
what kind of mineral spirits it is, it should perform as one would
expect of MS.

I had applied stripper to a small area of my work and, when time for
clean-up, I opened the new gallon of MS and found it to be milky and
somewhat thick flowing. Despite this, I decided to use it, since, I
asssumed, it is MS (even with it being vastly different than what I
was familiar with). It did not perform as normal MS. I stopped using
it, at that moment, and stained some through a paper towel, in order
to clean up my stripper. The straining process left a thicker sludge
on the paper towel and the stained amount was still not a watery
substance, as "normal" MS is. I decided to use the stained amount,
anyway, since I needed to cleanup what I had already stripped.

It left a layered "residue" on the woodwork, which I assumed was still
some "sludge". This residue sludge was not the result of the
stripper's sludge, which I previously removed (as much as I could)
with paper towels. The MS was to be used for rinsing the remainder of
the stripper's sludge, not adding to it. I tried to remove any and
everything. After it dried, there was layered crud on the woodwork
and, to me, this crud was not the stripped & varnish residue, but was
the MS residue sludge.

I got my work piece cleaned up pretty well and inspected the liquid in
the gallon of MS. I poured half of it out and found the more I
poured, the thicker it was. There were even a few soft lumps that
poured out.... at first I thought these lumps were large bubbles. To
this point, I still hadn't reread the label to see if there was
something to explain this... MS is supposed to be MS, so I was
"reading" what the liquid was telling me, not the container's label.

I had bought 2 gallons and, without breaking the seal on the other
gallon, I shook it to see if I could determine if this other gallon
may be thick, also. I couldn't tell.

My project wasn't damaged, in any way, but I did have to do more
cleaning up, than I normally do, because of this particular gallon of
MS.

Yes, I guess it pays to read a label, but hell, MS is supposed to be
MS and act and be like MS, I would think. Maybe this Green stuff has a
shelf life..... (Is that on the label? I won't bother to reread the
label, to see.). To me, something was wrong with this gallon of MS,
at least for my purpose. The stripper's instructions for cleanup was
to use MS. There wasn't anything abnormal with the stripper, to
attribute to this issue.

I returned the Green and bought some clear. My project is coming
along nicely, now.

Sonny