Several times… David Souter being a recent example… Republican appointees to this high office have proven to be more moderate than expected, some even skewing liberal quite often.
In every Presidential election year for the last half century, Republican appointed members of the Supreme Court have outnumbered Democrat appointees… except the 2016 tie at 4-4 because of the GOP stealing Obama’s final appointment opportunity. For most of that time the imbalance was 7 Republican appointees to just 2 Democrat appointees. In 1992, there was an 8 to 1 imbalance!
But in all that time, the decisions rendered were often regarded by most citizens as tilting liberal.