If you can find a single instance you are much more adept at it than the research firm my company hired last year to do just that. I'm afraid not. That is your opinion. Unfortunately there are many people, like yourself, who think that if they have an opinion, and they yell it loud enough, it becomes a fact. I defy you to disprove the first respondant to the post.
Towers raise property values, period.
You can look all you want, and you will never be able to find a single instance of property being assessed at a lower value because a tower is in sight. The same is true of telephone poles. While I agree with you that they are not the greatest to look at, they do raise property values. There are no studies by any credible sources whatsoever. You who oppose towers can go to your local assessors office and do a little research on your own.