It’s worth being particularly careful of boastful self descriptions; or, worse, boastful self-descriptions that appear to be neutral or even self-deprecating. It’s the equivalent of giving yourself a nickname like ‘Dutch’ or ‘Ace’ and hoping it sticks. You are asking to be bullied. Some are obvious. If you describe yourself as a ‘maverick’, a ‘cynic’, a ‘reprobate’, a ‘provocateur’, a ‘wag’, or similar, you are on a sure course for others to apply less flattering descriptions to you.
But others are subtler: ‘sceptic’, ‘realist, “radical or “progressive’ are all essentially boasts masquerading as statements of fact. ‘Sceptic’ says: ‘I’m the sort of person who thinks critically about what I read or hear.’ Since everyone presumably aspires to do just that, you’re trying to say you’re cleverer than those around you. ‘Radical’ means nothing at all, in this context, except that the speaker thinks that there’s a particular disruptive bravery to his her political persona – which is a judgment for others to make.