Adding -ed and -s

[jack]

Are these correct and what's the difference in meaning between them?

1.You smell like an opened can of sardine.
2.You smell like an opened can of sardines.

3.You smell like an open can of sardines.
4.You smell like an open can of sardine.

[Tdol]

3 is the best, but 2 is OK. 1&4 don't work because we have a number of the fish in any can.