Even hippos can be alright. I rather liked the Giff in Spelljammer. I can accept pretty random combinations of races in a game as long as it's baked into the setting. I want a relatively small number of races (less than 10) with a history of their interactions, current geopolitical situation, current attitudes towards each other, psychology of the races, and so on, all developed in a logical manner and with the consequences of all racial oddness reflected in the setting. I read a Sanderson book with some _very_ odd races recently, humans that can take themselves apart, halflings that turn into giants in daytime, zombies animated by worms in their bodies, and so on, and it worked because the logical consequences of the races were reflected in the setting. On the other hand, dropping a dragonborn into the Hobbit isn't going to work for me, even though it's not nearly as weird as the others I mentioned, unless the place and consequence of dragonborn are fully developed in the setting.