There have been a few times recently when I needed to see what something looked like from the perspective of a non-privileged user. What I’ve done was find an example user & “impersonate” them.
When I’m done, I have to log out & back in.
It would be nice if I could stay “me” and just temporarily downgrade what I’m seeing.
But there aren’t many “visible” differences between trust level users. You won’t “see” much through your goggles unless you have heavily customized your trust level. These are mostly usage restrictions.
As a trust level 3, you’ll be able to edit title/categories from others’ topics, stuff like this, but that doesn’t seem that interesting to “see” until you know, and there is little to know. You could have a secondary account and change its trust level before impersonating it, it’s a matter of a few seconds. This is what I do.
Have you some valuable examples of what you’d be interested in seeing through these “goggles”? 
Yes, exactly. Shortly after I gained global admin, I completely forgot which parts were and were not visible to me prior to gaining the privs. I’d like to see what lower-level users can see/do before I tell them to use features they don’t have access to.
create a test user and use it for testing.
problem solved
I have a test user logged in with a different browser (ie. me in Chrome, and test user in Firefox) so I can swop between them easily. I also sometimes use an incognito/private window, but that’s only good for anon things, and not logged in things.
I think something similar was requested recently in this topic:
We discussed this feature a bit here:
We do agree that there is a common desire to be able to “impersonate down” to TL1 etc. It is something that cal help theme component designers quite a lot cause sometimes you lean on staff features by mistake and then get surprised when the component is deployed to production.