If you find evidence of badly made repairs, avoid any such car.

If you find evidence that the engine has been repaired with inaccuracy (too much bulging of gasket maker, as in the image, loose bolts, stripped treads, altered wiring, broken fastenings, missing bolts or covers, etc.), avoid buying such a car because quality repair is possible only by very skilled mechanics. Just imagine how the engine has been repaired on the inside if it looks this way on the outside?