It's equally unrealistic to assume that UBI will exactly affect salaries by canceling them out. You're right that there will be effects, and they're likely to be dependent on job as well.

For instance basic income may mean salaries go up for the jobs nobody wants to do as people are given an alternative, while salaries go down for jobs that are intrinsically motivating.

I can't say for certainty though. My best guess is that it's going to be better than the hodgepodge of social welfare (and its complex effects) we have today.