Spanish Imperfect vs. Preterite Confusion.?

Yes it is a physical attribute. El estaba cansado(no consado)means that he was tire for a period of time and then he get better.El estuvo cansado,means he was tire for the rest of the day or shift,etc. The best translation is: El estaba cansado.About : "The food was good", The best translation is : "La comida fue rica." Because when you said "la comida era rica". Means "the food was good for a short time but suddenly some thing happend and the food no longer was good.