"You know if you were to do this to the artwork then I might buy it."
Really, if you don't like an artwork don't insult the artist with your preferences. Most professionals sell their work to people who become clients, followers, patrons, or the general public. If the artwork is not your cup of tea, then be polite. Don't offer up a critique at an event. Artists have their own view and voice. They take lessons from peers or people they consider better than themselves and learn from them.
Art is also subjective. As an artist myself, who also owned a gallery for ten years, I found I could sell any type of art to anyone. Once I even had an artist come in who needed to become a tattoo artist. I found him a teacher, now he is making boo-coo bucks in Texas with a shop full of tattoo artists learning under his tutelage. I did not think his art would sell in the regular market without some type of backstory. Now his art sells as much as his tattoos because he has one heck of a backstory.
In the artwork below, the arms of the subject are missing. My viewer wanted me to add arms and they completely rejected publicly my imagery. But I paint these figures to move the viewer to embrace the art. The art cannot embrace the viewer, they have no arms...that is my subject and point in The Androgynous Series. naturally this one sold. There is always something on my website for sale. https://pnwartistcatalog.wixsite.com/cgc-art-designs
In the long run, it is perfectly fine if you don't like the art, but it is considered both passe and rude to announce your preferences if they are different than the artist.