Suppose someone is presenting at a mathematics conference. He or she wants to soften up some of the less-technical slides with relevant images from a site like Pexels. It seems to me that, at least in the presentation's that I've attended (which are usually presentations for Master's and PhD students) that this isn't done too often; usually if a slide in a mathematics presentation has a picture, it is either meant to help convey a technical idea, or else it's a picture of the originator of an idea, or something like that.
Question. Is there reason to be concerned about how the presentation would be recieved in the context of a conference for professional mathematicians?
Assume that the creator of the presentation has e.g. the cultural sensitivity to ensure nothing potentially offensive is included, and the artistic sensitivity to ensure that images are not overused to the point where they're obviously distracting rather than helpful.
Edit. There was a request for concrete examples.
Maybe your presentation is about optimal timing of traffic lights, and you have a slide with a traffic jam in your description of the problem (assuming traffic jams are related to timing of traffic lights of course, which I'm not sure they are).
Maybe you're talking about encryption, and in the slide where you want to talk about the difficulty of breaking any given protocol, you have a slightly cartoonish image of a "hacker" on a computer trying to "break" it.
You're talking about mathematical models of the distribution of major earthquakes, and in one of your early slides you have an image of an earthquake occurring.
So, the question is really about images that are not really conveying a technical idea, but they're still relevant. They're used to make the presentation feel a bit less dry and technical and to orient the audience toward the theme being discussed by the presenter and the time the slide is displayed.
Edit2. I'd like to argue against the closure of this question. It asks questions that everyone at some point needs to ask if they're to develop their career in math research, and consequently has wide applicability. It's most easily answered by people already at a research level, and, since it's a question about the perceived appropriateness and professionalism of a particular practice in a particular community, it has objective answer that isn't too opinion-based.