Conversation so far:
What did Madvacharya believe?
Madhvacharya was a fierce critic of competing Vedanta schools, and other schools of Indian philosophies.
Why did he oppose them?
accusing Shankara and Advaitins for example, as "deceitful demons" teaching Buddhism under the cover of Vedanta.

Question: Did Madhvacharya have any issues with other guru's?
Self-contained rewrite: Besides Shankara and Advaitins, Did Madhvacharya have any issues with other guru's?