Not exactly a liar, but a servant of the Supreme, who descended for a very specific reason... The quote is from the Padma Purana. Here is a link to a nice article. Spiritual Leaders - Gaudiya-Vaisnava Acaryas - Sri Shankaracarya Actually we see Shankaracharya as a bone fide acharya
That is a paradox. I am not sure you understand the full implication of what you are saying here. Let me explain.
Shiva took birth as Shankara with the sole intention of lying and deceiving people. He filled his Sutra-Bhashya, Upanishad Bhashyas, UPadesha saahasri, Soundarya Lahari, etc., with lies, lied with a straight face to his disciples and left behind a legacy full of lies which - for over a thousand years - is being cluelessly followed by hundreds of thousands of Advaitins - who were never Buddhists or had any association with Buddhism. Perhaps Shankara was laughing inside as well, when he was teaching his disciples at how he was conning them, big time?
Even worse, Shiva is a God who lies to his disciplies and devotees (whatever his reasons may be) and we have millions of people in India who are Shiva worshippers and are unaware that their Ishta Devata is a cheap liar.
This is essentially what you are saying when you stand by that verse. If you want to take this positon, I am absolutely fine. But having implied all of that, you contradict yourself when you claim high respect for Shankara.
Like I said earlier, Madhvas claim that Shankara was a demon. But
1) They are consistent in that they do not claim respect or regard for Shankara
2) They never take this criticism outside their own tradition. When talking to Advaitins, they always debate based on scriptural interpretations. Shankara's demon status or Madhva's avatar status are never factors in the debate.
Again we come to the most important point - no matter what position we take, I am sure we agree that we require to find a spiritual master. He is the final word. I accept what my spiritual master says with full faith.
Regardless of who said it, calling Shankara a liar and also claiming deep respect for him do not go together. Now if people want to pretend it is not a contradiction and everything is just fine, then so be it. It is the easy way out, after all.