Well I learned about it from a meme, but there is indeed research:
https://www.govtrack.us/congress/members/report-cards/2020/senate/ideology
GovTrack's methodology isn't unassailable (they still have to figure out how to score certain legislative actions to produce these report cards), but it it repeatable and impartial.
Well that tracks. Cult leaders don't really like to acknowledge other cults.