In the Vishnu Purana it says that Vishnu incarnated as Buddha to teach false teachings to some demons so that they would be subdued and lose their powers, allowing them to be killed. It doesn’t say that Buddha’s teachings are good but it implies they are a false trick. Many Hindus apparently hear or read that Buddha is considered an incarnation of Vishnu, but very few are actually aware of the details of how this is described and what this entails and how it implies that Buddha’s teachings are actually still bad and something to be cast aside. It also says that Vishnu appeared as the founder of Jainism as part of the same trick of fooling demons.

>In order to defeat the demons ( daityas ) who had succeeded in obtaining great powers through religious austerities, Visnu came down to earth disguised as an ascetic and began teaching doctrines contrary to the Vedas. First, disguising himself as the founder of the Jaina school, he taught the doctrine of anekāntavāda (perspectivism or “non-one-sidedness”) to the group of demons. Then, moving on to another group, he changed his outfit and, appearing as the Buddha, taught that animal sacrifices are immoral and so forth. By this means, the demons lost all of the powers they had attained, and were summarily massacred by the gods.
>This story is remarkable because it accomplishes two goals simultaneously. First, it manages to subsume Buddhism and Jainism under orthodox Brahmanism, by demonstrating that both Mahāvīra (if that is indeed who is portrayed—he is nameless in the Visnu Purāna ) and the Buddha were incarnations of Visnu. Second, it completely discredits the actual content of the doctrines of these two sects, by suggesting that the teachings of Buddhism and Jainism are intentionally false and nonsensical. The dupes are the Buddhists and Jainas, who do not understand that the source of all of the teachings they defend so vehemently is a divine trick.