for all they were worth

[bartholomew]

They were patronising him for all they were worth (two coaches)

For all they were worth..what does that mean?

[Grunty]

Somebody will have a better answer, but I always thought it meant as much as they were able to.

[Quizmonster]

Such expressions were originally American. In fact the earliest one recorded is in the writings of Mark Twain. He wrote: "We shall fly our comet for all it is worth." It has nothing to do with 'value' directly, as 'worth' would normally suggest, but merely implies - as Grunty says - that effort will be applied to the maximum extent.

[Litchick]

Yes, I agree -- it sounds as if it should say  "with all or everything they've got..." or something like that...