As mentioned over here, you can remove your own blood from fabric with your own saliva, but you can’t remove someone else’s blood from fabric with your saliva. Would there be a good biological reason for this?
I expect that saliva removes blood with quite variable efficacy, but apart from that, I would think any person’s saliva would work as well as anyone else’s, on anyone’s blood.
So I suspect the reason it didn’t work with your mother’s blood is either pure chance (it is a very small sample size upon which you base the assertion), or that by the time you saw it, the blood had been on the fabric longer than if it had been your own.
I don’t dare click that link first thing in the morning. Blood is bad enough at breakfast time without saliva mixed in.
It’s just a link to another thread where gigi said pretty much the same thing.
bump…I know it sounds like an old wives’ tale, but I’ve heard it first-hand from enough people to think there might be something to it.
I suppose it’s just about possible that saliva from a person of one blood group might react and clot when mixed with the blood of someone of another group, but even this seems a long shot.
I was thinking this, as well. There are, after all, antibodies present in saliva.
Maybe it’s because the closest saliva available to remove blood stains comes from the same person as the blood. These stains are much harder to remove the longer they stand.
This sounds like an ideal challenge for Mythbusters… Don’t you have some connection with that show, Q.E.D.?
I thought about signing up on their message board to suggest it, but it doesn’t look likely that they actually look at the suggestions made there, and the place is worse than Yahoo Answers.
As chaotic as the fan board appears, they actually do cull most of their ideas these days from it, so I’d start there. I’m just a lowly researcher and all I could do is suggest it to the PTB; they don’t necessarily listen to me. 
OK, I’ll sign up and suggest it…
Or I might try the experiment at home with my family (my blood only, vs saliva samples from all four of us, plus an untreated control)
Wow, you really will eat anything! Thanks for going above and beyond.
Anybody who is licking other people’s blood stains has bigger issues than laundry problems! 
I think hygiene would be a good enough reason, but not efficacy.
You’re not supposed to lick the blood, you’re supposed to spit on it.
There, I’ve now taken the lazy man’s way of subscribing to this thread by posting to it, 'cause I’m curious as heck about whether this might possibly be true. I can’t imagine why it would be, but I suppose stranger things have happened.
Oh, I lick at it and suck on the fabric. It’s usually in the middle of some pure white area and I panic and go overboard. Plus there’s that oral fixation…
My WAS-EG is that when it’s your own blood, you are getting to it right away, before the red blood cells break open and spill all that hemoglobin into the fabric. Thus saliva, cold water, or a variety of other standard techniques will remove it.
When it’s someone else’s blood, it probably has had a chance to have the red cells lyse, and then the stain will be very very hard to remove.
For the record, if I get around to trying this experiment, I most certainly do not expect other people to ingest my blood - different methods of sucking etc could confound the measurements - we will apply the saliva with cotton swabs (I don’t expect this to be as effective in removing any of the stains as would sucking the cloth, but if there’s a difference in the way my saliva works against theirs, it should still be measurable this way.
Erm, you do realise this is no sort of confirmation at all? As the old saying goes, the plural of “anecdote” is not “data”.
Absolutely. I just meant that
old wives’ tale ('I heard that…") < anecdotes (“I’ve done it”) < controlled experiments
so it’s a step up from urban legend.