Why are some Ford cars (like the Taurus and Focus) such unreliable cars?

I'm looking at cars in the $3000 - $4500 range and I'm noticing a decent amount of Ford Taurus's and Focus's and out of all the cars that I see, these are two cars that just seem so unreliable. I test drove a Focus last year and it sounded like something was wrong with the engine.

Crown vics are more reliable. Cops use them.

Fix
Or
Replace
Daily

Ford has come a long way in the last 8 or so years… The overall quality, fit and finish and reliability of Ford is second to none for domestics… Not to mention they are making some beautiful new cars and trucks