First things first - what kind of language do we use in the speech.

Keep in mind that the great speechwriters always used simple easy to understand language, that's the secret of effective communication.   Audiences are far more sophisticated than in the past, dazzling them with your with your difficult words and phrases doesn't work, plain language they can understand readily is the most effective method of getting your message across.   Remember too that you must reach everyone in the audience at their particular level of understanding.   It is your responsibility to reach them, not their responsibility to understand you.   Great communicators of yesterday and today have always followed the kiss principal when writing their presentations.   Keeping you language understandable is a matter of examining all your words and phrases and making changes that simplify rather than complicate.

This is not to say that you fail to use language that fits the vernacular of the audience.   When speaking to professionals or to a mixed audience one must use suitable language that reaches the majority of the persons listening.   With a mixed audience you should aim for the median or middle that will assure that the majority will relate to your language.   Be sure to eliminate slang or buzz words or phrases.   Many popular so-called "buzz" words usually popularized by the media tend to be used, often a speaker feels that using them reaches the audience at their level, in fact the opposite is true.   Audiences expect high standard from speakers and the use of these terms does not show respect for their standards or expectations " give them your best and more".

I'm sure that it is common sense that no swear words should ever be used in a presentation, even the odd popularly used swear word is unacceptable.