Modifiers matching grump:

• mean,
• grouchy,
• gruff,
• arrogant,
• covetous,
• grizzled,
• impatient,
• condescending,
• ill-tempered,
• rich,
• miserly,
• wealthy,
• jealous,
• misanthropic,
• principled,
• fastidious,
• greedy,
• penny-pinching,
• heartless,

Simple categories matching fastidious:

• grump,
• person,
• miser,
• psychiatrist,
• detective,
• snob,
• businessman,
• foreigner,
• gentleman,