Undoubtedly, Shankaracharya is an authority in Hindu/ Sanatan religion. He says that Sai Baba worship is unhindu.


http://indiatoday.intoday.in/story/do-not-worship-shirdi-sai-baba-says-shankaracharya/1/368207.html

Sai Baba is also believed to be of Muslim origin. But some Muslinms have asserted that they worhip only Allah and nobody else. Sai Baba issue concerns only Hindus as they only worship statues.

http://timesofindia.indiatimes.com/city/allahabad/No-more-victims-Allahabad-girls-fight-their-fears/articleshow/37111312.cms?utm_source=newsletter&utm_medium=referral&utm_campaign=digest_section

However there are even self styled Gurus who get themselves worshipped. Undoubtedly, the Hindus are exploited and cheated by so many religious trusts in name of various deities and so called saints.

Shankaracharya says that Sai Baba is a human. Hence should not be worshipped. But Ram, one of the 10 incarnations is also Human as described in Puranas.

Religion is a set of beliefs. Ramayaa and Mahabharata are ancient Hindu books and so Rama and Krishna are very much worshipped as Vishnu- incarnate. There are some deities like Ganesh, Laxmi who are also worshipped in Sanatan Hindu tradition. On the other hand nobody knew about Sai Baba a few decades ago. The movie Amar Akbar, Antony got him publicity. Shankaracharya has just caution against worsip of Sai Baba abd other newly discovered 'gods', who are not part of Sanatan Dharama.

In fact, the worship activity is also a roaring business. The Holymenn at religious places make a lot of money by cheating devotees. This was well described in the movie 'Sangarsh'. As worship is a big business, there is a tendency to create new gods and make money therefrom. It is also possibe that traditional Hindu Sanatan Dharma faces stiff competition for new 'worship business houses' like Sai Baba and some other 'maths'.

Religion is a set of beliefs translated into commerce by certain limited sections of followers since time immemorial. Why should only they have the right to do so. As happens in commerce either they should share the earnings with others or some others will invent new gods and earn out of it. Religion ultimately is business of faith. Like all businesses it also finds new investors from time to time.

Everybody has its own belief and in country like India which is called the biggest democratic country everyone has the right to worship whomsoever he/she wants.