I don't mind them (as someone who has donated to servers in the past, after running a server that could be considered a donation server, AND after running a server that wasn't at all considered a donation server) so long as they adhere to the following:
1. The administrator in charge of the donations PAYS FOR THE SERVER. Sorry, Euphorian, supporting your drug addiction does not count.
2. The server expenses are transparent; Meaning they're known throughout the community.
3. The administration does something POSITIVE with the excess donations. Servers such as AnimaRO/AnthemRO have donated to charities (Child's Play) in the past and my former server was able to donate $500 to the American Red Cross with excess donations after a holiday sale.
4. The donation items can also be obtained by members through other means apart from donating if they're not able to do so. A voting center, ad credit system or similar does justice.
So long as the server's fun and there are players, I'll more than happily donate if I don't feel like I'm wasting money, whether for "over powered" items or for something as simple as a disguised non-statted headgear.
In regards to being on the administration side, however, I've run two vastly different servers in the past; SerenityRO and ElysiumRO. On SerenityRO you could purchase quite a few items that gave the advantage of instant gratification however non-donors could also get these same items in the economy, through voting or by helping out with tasks I posted revolving around coding/etc. With that system in place it worked effectively for two and a half years.
On the other hand, on ElysiumRO, donors had no advantage other than instantly being able to obtain small donation perks such as disguised non-statted headgears, etc. Because of this the server only lasted for two months since donations were not enough to cover the expenses of the server by a long-shot.
Ultimately, it's a case-by-case thing in my opinion. Some server owners are not good stewards with their donations and thus it reflects poorly upon the entire server, whereas others take care of business and do exactly what they say they're going to do. And as far as the strength of donation items/advantage they give, again, so long as normal players have "access" to them, I see no problem, especially if all it takes is a month or two of voting to get the same rewards.
I'd love to see where this thread goes though! I know so many people have so many differing thoughts on the matter.