When it comes to opinions... everyone has one.
I did a design once and my client said "I don't like that color green".
Since this is a personal opinion you can't say "you are wrong.. that's a wonderful shade of green".
But here's the "rub"... it was (in my opinion) the PERFECT shade of green. It was dark enough to pop my headline out of. It evoked the "earthy" feel that I was looking for. It wouldn't print too dark. It had everything going for it except for one thing.
My client didn't like it.
Now we all know how simple it is to change a color... but we don't want to go through endless rounds of changes finding, what your client perceives as "the perfect green". IF your client has a pantone book of colors, then it's easy. "just tell me which color you like". Done. But if your client doesn't have a pantone book, you can aways make some swatches of colors that you feel would still work.
But let me tell you how I handled it.
When my client said "I don't like that color green" I remained silent and waited to see what else my client wanted to say. After a very long pause.......... my client said:
"But I think it will work".
Bottom line: Help your clients, but don't get into an ego match over personal opinions. Give your client the best that you have to offer. And let your clients work things out for themselves. You don't have to respond to every comment unless asked. Many times they are just working things out for themselves and will take advantage of your professional expertise. That's what they are paying you for.