Bottled Bird Nest Taste

Does anyone knows why does Eu Yang Sang Superior Bottled Bird Nest tastes abit Fishy/Crabby? The rock sugar drink was fragrance though... The bird nest was taken from caves it seems. Has the taste of the birdnest got to do with the quality of bird nest? I remember having a bowl of nice refreshing bird nest in Bangkok restaurant & it didnt taste like that... Can someone recommend what other brands will have better taste?