Well, maybe a bad dashboard doesn't mean the whole car is horrible, but it can certainly change the way you feel about a car. Even a single bad *detail* can ruin the experience for you.
I remember back around 1969, my mom bought a Buick Skylark: forest green, with a black vinyl roof. Very chic for the era. In most respects it was a pretty good car for 1969, especially with the optional 8 cylinder engine that put out 230 HP. Nobody balked at 12 MPG fuel economy back then. It was even rather good looking -- maybe not in the same league as a classic Mustang, but brawny and compact for 1969. Check out the Sports Coupe on this page. That's it, fourth from the top. Mom's car.
This car had one fatal flaw: the climate control UI. That was an impressive "space age" affair in which the settings were made on a thumb wheel and displayed on a bar graph. The graph even turned red when you went from AC to heat. Here it is on ebay. Look closely at the worm gear mechanism used to operate the bar readout. This was a fatal flaw that turned what would have been a very nice car into a lemon.
Unlike the basic lever and cable arrangement in less expensive cars, with this you have no tactile feedback. You can't feel whether you've set the control to AC or heat, much less how much heat you've called for. Check out the worm gear mechanism in the photos. That meant you had to rotate the knob maybe three times to go from max AC to max heat. Since only part of the knob protruded from the faceplate you could maybe rotate it 60 degrees with one swipe of your thumb. So when you wanted to change the temperature, you had to take your eyes off the road to see the bar graph, then often frob the control wheel with your thumb five or six times to get the setting you wanted.
I remember my Mom cursing that car every time she wanted to change the temperature. It was one small detail that ruined what would otherwise have been a terrific car. This is the first car I remember in detail, and it taught me an important lesson about user interfaces: impressive controls and displays don't necessarily make a UI convenient or pleasant to use.