Pretty pessimistic persons, characteristically? (5)

I believe the answer is:

types

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'pretty pessimistic persons' is the definition.
'types' can be an answer for 'persons' (type is a kind of person). I am unsure of the 'pretty pessimistic' bit.

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for types that I've seen before include "Sorts; kinds" , "Characters" , "Uses a keyboard; sorts" , "Sorts - varieties" , "Classes or groups" .)

I've seen this clue in the Evening Standard.

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