How many letters does the top answer for “the quality of being difficult to detect or analyze” have?

The most common answer is niceness (8 letters).

Crossword clue: the quality of being difficult to detect or analyze

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

niceness 8 letters wn-def

the quality of being difficult to detect or analyze

subtlety 8 letters wn-def

the quality of being difficult to detect or analyze

the quality of being difficult to do 50% similar → ruggedness