Have a look
here.
Describing
character is what you're confusing, I think.
If something is characteristically delicious, use
ser. If it
surprises you that something is suddenly delicious, use
estar.
If someone is characteristically beautiful, use
ser. If you are
surprised by someone's sudden beauty, use
estar.
Something is not usually dirty (characteristically), so we use
estar.
Someone's health is either characteristic, or is a change from the norm. For the first condition, use
ser. For the second, use
estar.
Ser enfermo (sickly person)
Estar enfermo (sick person)