Almost every client is concerned with aesthetics. Sometimes people are more concerned with safety...but if they weren't concerned with aesthetics as well, they'd just remove the tree. Orchard production comes to mind where aesthetics is probably not important.
But what does that mean? Japanese maple has been mentioned a few times. Some people shear them and they look like a giant overgrown bush...and some people like that. If it hasn't been sheared too bad, I like to suggest that we take the bush and make it look like a proper tree. Thin it out enough to see the trunk and branch structure...but not whack the heck out of it.
What about crabapples that people think should look like a lollipop? I usually get that request when the tree is 20' tall and wide and there has been little or no previous maintenance. They want it to look like the one down the street that is 4-5' wide, a different cultivar, and much younger and gets trimmed/sheared 2x per year. I don't know how to pull that off. Even on a young tree, I can usually talk folks out of that when the understand the level of maintenance it takes...
For big trees that people want "shaped" - there are often a few limbs that are longer to one side whose reduction will give the tree more symmetry, but I point out that with a large tree we are beyond dictating shape and form - that needed to happen when they were younger - and we should focus on pruning to reduce the hazards (dead/broken/poorly attached) and perhaps a few branches that are in places causing problems (traffic, against a building, etc...). "Less is more" is the phrase I like to use when pruning healthy larger trees.
Even though many clients may have one thing in mind, they are generally accepting of expert advise.
