Stubborn Stains Of Unknown Origin

[mabaker]

Nothing sinister

I'm having dfficulty removing stubborn spot stains from two white shirts, 2 spots per shirt. I've tried vanish stick pre-wash and oxiclean directly as instructed but they won't budge. I have no notion of their origin and am now contemplating using neat bleach just on the spots themselves, any advice before i jump in.
Not sure I would recommend either of the products above but I'm going to try oxiclean as a pre soak to see if this improves general whiteness.
Will let you know what I think.

Neat bleach might leave you with yellow spots, though, even if it removes the stains.

I've put a small amount of neat bleach on white 100% cotton tshirts before now and it's worked well. I've rinsed it off pretty quickly.

I have a similar dilemma of my own, wonder if anyone can help? I have a white tshirt (cotton/elastane) which I washed with some turquoise bedding... It has taken on the colour around the underarms, I guess it must be something to do with the deodorant, anyway nothing is shifting it. It's been soaking in a strong bleach solution since 11 this morning and is still blue. Any ideas - have tried colour run removers already, maybe it's a lost cause.

Thanks - and sorry, don't mean to hijack, mabaker, just hoping the two issues complement each other!