Art is an extremely personal thing. What is appealing to some may be unappealing to others. What makes great art is not necessarily 'great' for interior design esthetics that are helpful for marketing purposes. Yes, the art may be brilliant, highly valuable collector-quality, but for the sake of marketing some art has the capacity to distract and even deter buyers.
Art in homes varies from decoration to gallery-like installations. I know of a 20,000-plus square foot one-bedroom home in Dallas designed by Pritzker prize-winning architect Richard Meier that was built mostly to house a world-class art collection. It is phenomenal. But is it a home or is it a gallery? This varies from individual to individual. Homes are extremely personal. What you find ridiculous, others may deem extraordinarily wonderful.
As a real estate marketer, I have to evaluate art based on my understanding of my potential audience. If an art collection - or individual piece - is almost certain to minimize your potential audience/buyer pool so dramatically that it will impact valuation negatively, I need to communicate that clearly - and delicately - to our clients. Some highly prolific art collections though will appeal to a certain audience and ADD value. An impressive art collection can elevate any property.
Distractions of any kind are not healthy in the real estate marketing equation. Instead of critiquing a client's art, maybe it's wiser to merely focus on the following: "This home has to appeal to the widest possible audience to maximize value. All distractions or anything that's too personal will simply take away from the buyer's ability to imagine themselves in this home. We are selling a canvas for the next owner's life."