They ADDED a bridge tap to my DSL line about a year after it was installed. That completely screwed up my DSL -- I didn't get anything until it was fixed -- which required a couple calls to my ISP, two PacBell trips (they didn't fix it the first time), and a Covad trip (since somehow one of the wires at the wiring box became disconnected).
So, yes, bridge tap == very bad for DSL
Tony