replicate-wild-ignore-table does not stop already logged queries on slave
Without seeing the exact my.cnf entries on the slave, or knowing where the update came from (normal UPDATE command, or a stored procedure for example), or knowing what type of binary log format (row vs statement) you are using, all I can do is give you a link to how MySQL handles the replicate table options here.

A couple of things to note on this to explain why the above points are needed:


If you are using statement based logging and the statements are executed from a stored procedure, the slave will run it because --replicate-table rules do not apply to stored objects.
If the table name you are trying to ignore contains an underscore, you might need to escape it like "foo_bar". The same applies to the database name.