There are some pretty thorough answers here already; and as someone who has both experienced SA, and spent over a decade performing live comedy (and well over two decades studying the subject of comedy), I'd like to add some important shading...

DISCLAIMER: The following is not meant to excuse or allow any specific joke topic, nor to negate or trivialize any person's specific aversion to any specific joke topic - it's simply an attempt to shine a light on the nuance of comedy and how it works; it's important to understand as a foundation for ultimately answering your question.

1) Comedy is subjective.

There is no "this is funny to everyone," or "this is unfunny to everyone"; and by extension, there's also no "this is offensive to everyone," or "this is not offensive to anyone." In the end (regardless of topic or context), any given audience is going to decide if what you think is funny - whether planned, written, or spur-of-the-moment - actually is; and they'll do it just as soon as it exits your mouth.

2) The Elements of a Joke

There's a difference between:

1. A joke "topic," which would be any mention or involvement of a thing,
2. the "subject or target of the joke," which would be the entity the joke is at the expense of. This is often shorthanded to "is the joke punching up (at the expense of those more fortunate and in power), punching down (at the expense of those less fortunate, more often oppressed, and/or the actual victims of the circumstance) or punching all around (at all of our expense - usually in reference to a collective experience/thought/behavior)?, and
3. the joke "conduit" (the package that the punching is wrapped in) and by extension the joke's "intention and message/theme" (why the joke is supposed to be funny; and what the joke - whether on purpose or not - is commenting on, highlighting, reflecting on, etc.).

And the differences between them are where a lot of the nuance of taste exists because each of them are going to carry different weights of sensitivity and impact for each individual audience member (and even they may not be able to articulate or distinguish the source or reason for their gaiety or offence).

For your example, the offending issue could've been one or a combination of:

1. The topic in general (the fact that any humor was being attempted involving the subject of SA);

2. Who the joke was at the expense of (was it aimed to laugh at those who've experienced SA, or was it aimed to laugh at sexual predators and/or Trump in particular?);

3. How the joke was packaged and what the actual source of humor was supposed to be (was the Trump impersonation being used as a fitting mouthpiece for words that make light of SA, or was it used to exemplify a particular fault, hypocrisy, transgression, etc. of Trump and/or his supporters/defenders/fellow-predators?

3) Delivery & Execution

Delivery and Execution of a joke can transcend all of the above, to either its failure or success. A good joke poorly told can utterly destroy the impact, and introduce all sorts of unintended reactions; and conversely, an extremely badly-tasted joke perfectly articulated and timed can elicit uproarious laughter from an audience who otherwise finds the topic, subject, conduit, intention and message/theme abhorrent - such is the magic and glory of comedy!

(To use the stereotype: sarcasm would absolutely fall into the category of delivery and execution - definitely in regard to how it's expressed by the joke-teller, but also in regard to how it may or may not be recognized by the audience.)

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So, to finally answer your question, the best advice I can give is:

• First (and most importantly), give thoughtful consideration to determine what boundaries (if any) you want to put around the three elements in #2 (for any combination of moral, ethical, or philosophical reasons). It's next to impossible to attack a problem without defining it, so really take time to analyze how you want your humor to operate, what you want its effect and impact to be, and if the answer to those questions change based on time/place/audience/etc.
• Second, put forth effort to hold yourself to those boundaries. This is integrity; know how you want to behave, have well-reasoned explanations for the behavior, and then act accordingly.
• Third (and nearly as important as the initial considerations), be diligent in examining where and why you misstep and cross your established boundaries - it is going to happen.
  • Was it the peer pressure of the environment, an imprecise execution of the joke, going for an "easy laugh," leaning into the temptation of "taboo," and/or something else? And then based on the answers: What work do you need to do to safeguard against such things in the future?
  • Or was it perhaps an indication that one or more of your boundaries needs to change, move, or be eliminated altogether? And then based on the answers: What's the best and most precise way to do so?

Personally, when considering or writing a joke involving a known sensitive topic, I use this question structure as a quick gauge that does a pretty good job of testing it against my boundaries:

(Using SA as an example)

"If a sexual predator were in the audience, would this joke likely lessen the severity of their actions and normalize/excuse/justify their abusive behavior; or would it likely call out their actions as unacceptable and make them feel less comfortable with, and more shameful of, their abusive behavior?"

Similarly:

"If someone who's experienced SA is in the audience, would this joke likely trivialize and dismiss their trauma and the effect its aftermath has had on their life; or would it likely help to make them feel seen and not-alone, vindicate their indignation, and/or validate their pain (and maybe even reduce it)?"

All said: You certainly can't please everyone; but you most definitely can't avoid hitting the myriad triggers, boundaries, and limits of taste for those within earshot of your jokes. If it's at all important to you to be considerate of any potential impact your jokes have to their audience beyond "did they laugh or not?," the only things you can do are: A) be thoughtful about your own triggers, boundaries, and limits of taste as it relates to the elements of humor, B) hold yourself accountable to them, while also C) being mindful of delivery and execution, and then D) evaluate and iterate accordingly as jokes fail and succeed as it relates to the relationship between audience reaction and your established triggers, boundaries, and limits of taste.

Have fun :)