Janey Godley says that the Gilded Balloon pissed her off and look what happened to it – one rather expensive fire. Tonight the lights flicker briefly and she's wisecracking about the “eighteen-year-olds” who run the venue needing to put another 50p in the meter. The Underbelly better watch its step, as Godley's gangster in-laws had her sexually abusive uncle killed for her birthday.

In Good Godley, where the facts end and the fiction begins is unclear. This is a masterful device in the hands of a warm, witty Glaswegian whose audience rapport extends to greeting punters on the way in and thanking them on the way out. It's not a novel strategy, but the impression she leaves is that she really – no, really – means it.

Her stories are her life story. Godley married a man with Asperger's syndrome at 16, lived in a pub in the east end of Glasgow, was better at being a mother to the cat than her baby daughter, and called Hugh Grant an “untalented cunt” when she got the chance. Naturally, the book deal is in the can, although she's having a few problems writing an autobiography that ends in an unsolved crime.

What's also deliciously ambiguous is whether Godley is a rampant self-publicist or simply one of those people that things happen to. She was first on the scene with a camera when a Glasgow plastics factory exploded in May; at last year's festival she convinced a suicidal man to change his mind and step down from the ledge. Perhaps she's both.

Either way, it's difficult to dislike a woman who has two voices in her head, one of which is a big black man who rogers her senseless whenever she lets her mind wander in the supermarket queue. In the hands of another, this would likely be offensive, but the candour and been-there-done-that wisdom with which Janey speaks on touchy subjects is her saviour. She likens herself to an “overfriendly cleaner” who's wandered on stage, and this year she scrubs up well.