Cheating
As Lex followed the major, he compiled all the information he had gathered about the robots and sent it to Mary. He informed her to give everything to Velma and have her add it to the information the Midnight newsroom sells privately.
Although he had already done a lot to paint the Innkeeper as biased towards humans, he began to change that perception by slowly doing these small things. Eventually, over time, other races would also get similar benefits which would erase the perception of bias.
Lex already had a vague idea of doing this, but lately his intuition began warning him that he was heading towards trouble if he kept up such behavior. In hindsight, it did seem like he was overly favoring humans, even though as of now, his most common guests were devils.