Why did my Chinese teacher describe Donald Trump as 口吐莲花?

口吐莲花/口吐芬芳 originally means someone's speech is 1, literately nice 2, pleasing to listen to.

But it really depends on the context, because people these days use these words in an ironic way and can mean the exact opposite. When people say someone 口吐莲花, they probably mean his speech is 1, totally nonsense 2, full of swear words.

Other examples of expression that are often used in ironic ways and means the exact opposite are:

• 文明用语: polite words / swear words
• 小嘴抹了蜜了(little mouth with honey on it): speaking pleasing words / speaking swear words

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).

The original meaning is to describe someone who has the gift of the gab. Here it is probably a satire on Trump's frequent nonsense.

口吐莲花 ( and 口吐芬芳） is a modern word online, e.g. in Dou Yin (TikTok Chinese version)

Mostly it's to show someone is saying dirty or ridiculous words.

Its original meaning is to say something is good, something is beautiful, or it is something that makes people happy.

口吐蓮花 means a person speaks in a well-versed and literarily appealing manner.

Its origin, according to Baidu (https://baike.baidu.com/item/%E5%8F%A3%E5%90%90%E8%8E%B2%E8%8A%B1/15258) is as follow:

“莲花”是佛教的象征，吉祥和清净的标志。说法微妙，谓之“口吐莲花”

Rough Translation:

Lotus is a symbol of Buddhism, it symbolises good fortune and purity. Speaking in a sophisticated manner could be called "口吐蓮花".

Example:

这位 (This, but in a respectful manner) 和尚 (monk) 说起 (talk about) 佛法 (the teaching of Buddhism) 来 口吐莲花

（This monk is well-versed when it comes to talking about Buddhism teaching)

As in why your teacher specifically used this word, they could be either sincere or satirical. Using it in a satirical manner could mean the speaker talks in a bizarre and non-sensible way or the content themselves are non-sense.

1. 「莲花出淤泥而不染」，象征纯洁 (lotus flower came from mud but not stained by it. Symbolizing purity.)

Your teacher described him as 口吐莲花 in an ironic way, mocking his foul mouth

2. Idiom 舌灿莲花: 譬喻说话的文采和美妙 ("the tongue sparks lotus flower" refers to having the literary talent to speak beautifully.)

Again, ironically, your teacher was mocking his lack of literary talent and his incoherent speeches