

If you don’t trust it, why use it? It’s still slop in the end, just somewhat less slopified.
Consider: either you are smarter than the tool you use, in which case it doesn’t really offer anything much, or you are dumber than the tool you use, in which case you wouldn’t be qualified to judge its results anyway.



False. Browsers can announce themselves as desktop or mobile, or even advertise pre-determined fake window and screen sizes for this purpose (in Firefox it’s called “letterboxed” in the hidden settings). There is no need for a server to have any of this information anyway - either the design of the webpage should be responsive by default, or the server can send specifically whichever files for styles the browser specifically asks for, perhaps falling back to a “all.css” or something.