Well, my hubby works on water lines, and usually comes home with:
a. mud
b. more mud
c. head to foot mud....ah, you get the picture.
I have good results with the home brew on his work clothes. Its been my experience that NOTHING does a serious good job on hydraulic fluid, that stuff is just horrendous, it gets MOST of it out, but the marks usually stay. Sometimes when he comes home head to foot mud, (when he is NOT allowed IN the house until he strips down in the mud room!) I do have to launder them twice, but only because they are just saturated with mud....
I hate water line breaks....and right now he's working a major water line project in Sykesville, so its mud every day!
Whites, well I use it with a touch of clorox. I refuse to wash my whites without bleach. I've never had much of an issue with armpit staining...so I can't really answer that one! Now my late mother would tell you, to put lemon juice on the stains, then sprinkle them with salt, and put them out in the sun to make them go away...never tried it, but hey you never know.....
On clothing that's already been stained, washed, and all that, it won't get out the old stains, but I can say I've been very happy with how it handles His Lordship's clothing. The nice fresh scent is a real bonus too. I use unscented drier sheets, and when I use the home brew, the clothes come out of the drier smelling like they've been dried outside....serious bonus.