I think this is mostly related to ethics, but it can also refer to having you do something that you normally wouldn't do that
is ethical, but you can be paid off to do.
I have an example - I'm an average software engineer in the midwest making $170K/year in a great field, and I've been offered a position in Dubai, in an outdated industry, making somewhat less salary, but 0% taxes and a housing and travel allowance.
Here is the thing - I love my current job, love the field, love the local weather, culture, apartment. I really don't want to move, don't really like the new field, really don't like living in Dubai (lived there for six months) - but, Net of Travel/Allowance/Salary/Housing/Taxes, I'll be making $50K more in pocket
At a certain point, money can buy your unhappiness. I guess we'll see if $50K is enough to do that for me.