Is it true that you can't tell for sure which bitcoin address
 sent you coins ?
 
 I asked about this when trying to understand how satoshi dice
 paid you your winnings to the bitcoin address you made your bet
 with.
 
 After some pondering and getting some help from this site, I'd
 like to ask this..
 
 Do sites like satoshi dice determine which address was used to
 send money, by generating a brand new bitcoin address which
 is displayed to the gambler to send coins to ?
 
 I don't think so - because satoshi dice use vanity addresses,
 and I would think it would be too difficult to generate this
 many of them..
 
 So the problem/question still remains - how do sites like satoshi
 dice, know who sent them coins ?