Is your teacher an anti-Trumpist? If so, she is ironicing(反讽) him, that is, deliberately describing Trump's "dirty" language as extremely pure.
The lotus flower in China always represents purity and nobleness, because it "is out of silt but not stained, and is clear and not gaudy" (Zhou Dunyi[周敦颐] in the Northern Song Dynasty[北宋], "Why Do I Love Lotus"[《爱莲说》]). Another example is the Southern Song[南宋] poet Yang Wanli[杨万里] wrote in "Little Pond"[《小池》], "The little lotus just started to grow up, but dragonflies have long been on it"(小荷才露尖尖角，早有蜻蜓立上头). But Trump’s words are not like this. His words are very offensive and often slander others. In the eyes of the Chinese people, this is "the words of a despicable person" and is dirty. This is in sharp contrast to the purity of lotus.
Irony is a commonly used rhetoric. Its definition is "It is impossible to understand what it really wants to express purely literally, but in fact its original meaning is just the opposite of what it can understand literally, and it is usually necessary to understand its meaning from the context." , The students are late, if the teacher is angry, sometimes they will say "you came so early". If someone does something stupid, you can mock him: "You are so smart!"
Therefore, if your teacher doesn't like Trump, the meaning of "口吐莲花" here is likely to be closer to "spitting dung in the mouth"(满口喷粪) or "dirty mouth"(出口成脏).