Not genuine, sincere or authentic: based on false idea or bad reasoning.
1) I saw a spurious Picasso painting that couldn't have fooled an art expert for a second.
2) Thet claimed that the governor's election year enthusisam for conservation was spurious, sincw he had cut funding for state parks.
Late Latin spurius meaning 'false', from Latin meaning 'illegitimate birth'.
bogus, fake, false, forged
authentic, bona fide, real.