If your television connections are going through an analog switch box, that could be the source of your "awful" picture.
Way back in the stone age, (the early 80's - I was a wee lad), when folks had many analog devices, (ON TV, VCR, Pong Console, Commodore Computer), connected to their television's one antenna input, (two screws using a balun adapter), there were switch boxes.
Now, in the 21st century digital age there are still AV switch boxes in your RV!
Back in early 80's If you had a bad picture with your paid subscription "ON TV" box, the visiting technician would first disassemble the switch box, (if you had one), and spray the internal electrical switch contacts with an aerosol can of electrical contact cleaner and lubricant.
Voila! The picture would be fantastic!
..... At least for a few weeks until the spray lubricant dried out and you had to call the technician back!
My 2014 Hurricane 34E came with an analog switch box. My DVD picture was "awful" and snowy. I remembered the past, and so I "exercised" the push buttons. Sure enough, the picture came in clear because I very likely wore off the layer of oxidation that had built up on the internal switch contacts.
If it ever gets really bad I might be inclined to remove the box, disassemble it and spray the internal switch contacts with aerosol contact cleaner and lube just like they did in the 80's! Or, just replace it with a cheap Monoprice model off of Amazon.