Ser vs Estar con adjetivos: esencia o estado

English: ser listo = “smart, clever” (a permanent quality), estar listo = “ready” (a current state). So we say: “es muy listo” + “está listo”. See the list of meanings for adjectives with ser/estar (listo) and the rule “ser = essence, estar = state.”

English: estar bueno (for food) = “tasty/delicious”, estar bueno (for a person) = “to be healthy / to have recovered”. ser bueno = “kind / good-quality” (doesn’t fit here). That’s why both forms are estar. For more details on the meanings of “bueno”, see the guide on adjectives with ser/estar.

English: estar aburrido = “I’m bored right now” (a temporary state). ser aburrido = “to be a boring person/thing by nature”. Here it’s a temporary state, so we use estar. See the difference with “aburrido.”

English: ser verde = “to be green (color)”, estar verde = “to be unripe (fruit)” or “inexperienced”. So: el coche es verde; los plátanos están verdes. See the meanings of “verde” with ser/estar.

English: for spoiled food we use estar malo/mala (“in bad condition, has gone off”). ser malo = “bad/evil/low quality (in general)”. Here the milk is spoiled → estar. See “malo” with ser/estar.

English: estar seguro (de que…) = “to be sure / certain (that…)”. ser seguro = “safe” (for a place/thing) or “self-confident” as a character trait. Here it’s certainty about a fact → estar. Examples: “Este barrio es seguro. Estoy seguro de que…”

English: ser nuevo = “brand new (just produced/bought)”. estar nuevo = “like new (looks almost new)”. Here it’s really new → ser. See “ser/estar nuevo.”

English: to talk about the taste of a dish we usually use estar rico/riquísimo. ser rico = “rich” (about a person). So: “está riquísimo”. See the differences of “rico” with ser/estar.