Opening Confession: Not sure why, but I have never liked any book set in the "art world." Is that because I find all them unrealistic, false, the work of someone expert in one world aping the language, norms, behavior, values, etc of another world in which they are a visitor? Or am I driven away from these for the same reasons I dropped out of my Art History MA program... I found the language, norms, behavior, values, etc unbearable on a daily basis?

Chicken? Egg?

That said: This book had too many plot holes, too many times the dialogue ran un-true, and the premise of it was based on too much invention supporting invention (as opposed to speculation filling gaps but built on substantiated fact) to hold together in a way that made it compelling. Either make it all up, or build your story out of a full array of facts. The epilogue that states THIS happened, THIS did not happen, THIS may have happened, THIS never happened is such a mishmash I ended up feeling as cheated on and lied to as the main character was by her dealer/lover.