Black marks about points exhibiting vulgarity (10)

I believe the answer is:

smuttiness

'vulgarity' is the definition.

'black marks about points' is the wordplay.
'black marks' becomes 'smuts'.
'about' is an insertion indicator.
'points' becomes 'tines'.
'smuts' placed around 'tines' is 'SMUTTINESS'.

'exhibiting' is the link.

(Another definition for smuttiness that I've seen is " Mild indecency".)

I've seen this clue in The Independent.

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