Bad Formula 1 teams don't exist anymore. Somebody will always be at the back, but everything is relative and even the weakest performer these days is, at worst, a credible and effective grand prix team.
This is one of the side effects of how enormous and complicated teams have become. They are now substantial edifices; even the smallest employ hundreds of people and spend vast sums of money to design, build and operate some of the most elaborate and specialised machines on the planet. Even to build a car and get on the grid requires formidable infrastructure and able personnel.
In many ways, that's a good thing. It gives grand prix racing stability thanks to 10 serious teams doing, at worst, a decent job. But F1 is not a purely scientific endeavour - it's a sport that thrives on emotion. So, the absence of the bad teams, the true minnows who either lack the resources or the knowhow to thrive, means there's also something missing. If nothing else, they would act as a barometer of how effective the rest of the grid is.