Yes, these situations do come up where one player makes a call that has
negative expectation for him and you and greatly adds to someone's positive
expectation.  I have done extensive work on game-thoeretic multi-way pots
but I'm not willing to share those calculations yet (since I don't know
whether they are right and don't know how valuable the info is..).

Let me give a simple lowball example.  Say you have a straight 98 and
raise-all-in a guy who has a [one card] wheel draw (you both are all in).  
You have a slight edge and expect to make money.  
But now suppose someone in the field decides to call with a [one card]
96-joker draw -- you are now decidedly a dog and so is the person who
called, but now the wheel draw is a big money favorite.  In both cases the
wheel draw only has to catch a 9 or better to win, but wins twice the money
in the second case.  If the two players against you are partners, calling
is the correct play.

Ok, a hold'em example--say you have T9s, your opponent has AQ and the board
shows QsJh4s3d.  Suppose the pot is 1.5P, and your opponent bets P and you
correctly call (say it's an all-in situation again).  Another opponent
whith the A-high flush draw now makes an incorrect (but seemingly reasonable)
call--now your only outs are the straight outs. and the caller has just
given yours and his expectation to the AQ.  

The point is that in all games there exist such players who you know will
make these incorrect calls--not because they cheat, but because they are
bad players.  You have to factor this into account and will turn some marginal
calls into real money (winner/losers).  

Rememebr this--marginal callers increase the value of big draws and strong
hands while they decrease the value of non-nut draws and marginally leading
hands.  Heads up, I will confidently play 2nd pair with a non-nut flush draw,
since I have a reasonable # of outs against any hand.  In a multi-way pot with
lots of heat i may have to drop.

This concept may seem backwards to most people but let me explain.
Say i have T9s again and the flop comes AsTh2s.  I have a marginal hand with a
marginal draw, but aginst either top pair (or even top set) I have outs.
Against a bigger draw, I currecntly have the lead.  Say I'm jammed in
with the same hand and flop multi-way--I may be drawing almost dead vs the nut
draw and AT.  

Bill