Hi. I wanted to get your guys' opinion on this.

Sometimes, when my HDTV is being used by somebody else in the household, I move my Roku 3 to another room that has a desktop monitor with an HDMI input. I don't really have enough room on the desk that the monitor, hard drive, keyboard and mouse are on. So I was thinking of just placing it on the carpet.

Is it safe to put the Roku on the carpet long term? Or would that be a bad idea and harm the Roku?

I wouldn't do that with mine, but that is because my apartment is floor-heated...

My Roku has no vents on the bottom, so I don't see why placement should matter (unless someone steps on it or the cable is too short).

I'd put it on a book or tablet or whatever else is handy that's hard just to be safe, especially if it's a Roku4.

I own a few small-ish electronic A/V components and have always found that placing the device on a hard surface is better than placing it on a carpet,especially if the carpet has a thick "pile".Have found devices run warmer,sometimes Much warmer (even Hot sometimes) when placed on carpet.
IMO carpet,because of the way it's made,has a lot of dead air spaces in it created by the "weave" of the carpet..The dead air spaces act much the same way as the dead air spaces in thermal underwear act.
The spaces collect/retain heat, but not disperse it very well.A hard object like a table collects heat,but it also reflects/radiates heat into the air much faster than dead air spaces do.Thus a device placed on a table will tend to stay cooler than on a carpet.