Releasing toxins is a contrivertial issue, however it will cause an anmomia spike, so that has to be gaurded against. Toxins also depend on the type of anemone.
Snot, melting ice cream are good discriptions when viewing a dieing anemone, the final is the smell, because its bad, real bad.
If you see parts of the mesenterial filaments or gametogenic tissue, then it's usually serious, sometimes you can see parts of the acontia coming out under the pedal disc but that can be normal.
Thomas