I know this has long been answered, but I want to add to that.
Its not always possible to even cite everything because their usually written as a response, an observation. A company isn't going to tell you all the faults with their product, unless its Internet and they've already released the newer version... As they did to V2 Megpoid when they released the V3. Users find out how bad or good a product is, AFTER its been released an then report back. ITs then confirmed by other fans. If its repeatable across various user's with different set ups, its an issue.
A few are simple pointing out flaws that people overlook when they don't read things. For example Piko's ranges not his a higher pitch male vocal so using him low is bad. So I've ended up noting that on the bad, even though you only have to look at the vocal range to see that. Likewise, Yukari's tempo range got noted not built for speed and Iroha's tone is not good for softer spoken lyrics. It seems fine, but people don't read nor know ness. how to read certain things so a few things are just blunt "Captain Obvious" because of it.
We can say "x vocaloid has a bad "R" phoneme or something but you can use it and because your ignorant on the "why" its you'd disagree. If you believed the fandom in 2010 then until VY1 arrived, Gumi was the most realistic Vocaloid, it wasn't. Discounting Yuki because there is some issues determine how realistic she is due to a lack of a provider, for the Japanese that was miki and English Prima. This was the sort of thing you can get. You say something and no one believe you because their ignorant otherwise. As someone whose written a great deal of these sections, their honestly hardest part of the wiki to write. It may be true, but the user may never encounter because they never use the Vocaloid in a particular way. So its not "true" to them.
Obviously we don't believe everything reported... See V2 English vocaloid. If we reported everything, we'd have completely nonsense and incorrect information on them. In addition a threat to voicebank sections, is there can be bias mixed in we have to be wary of.
@Viper, We can do other samples then do-ri-me, [[Sonika]], [[Tonio]], [[Prima]] and [[Big Al]] all have samples I added before it was a thing to just have them dorime. If users want to put up a introduction thats fine. Someone gave us a couple too to add to them.
vocaloid.wikia.com/wiki/File:Gakuposings.ogg
I would like to see this tradition return but it was never easy. The sample couldn't go past a minute and was usually aimed to be around 10-30 seconds. IT lead to problems with knowing what to write and how to instruct people how to do the samples. And then there was converting it to the sample format the wiki system uses, which few knew. When I asked for samples I only got 2 back. Dorime, certainly is easier to get responses from, but if people want to add introduction samples that fine and you can sort that out if you want. You've got my guide with Tonio, Sonika, Prima and Big Al. As well as the Gackpo and Kiyoteru ones.
I found it was near impossible to get these samples, whereas when we pulled up the "dorime", people seemed more willing. It could because VO forums had issues with me at the time, but it was still difficult. Just describing how to write the samples was tough. One issue I noted is it was RAW. That meant you weren't showing the Vocaloid at its best and this was a little unsettling for some in addition, as no one wants to actually show Len Act1 messing up when their just happy saying he does. Dorime, however, puts all the Vocaloids on the same level playing field.
The rough guide is;
*One sentence and make it count!
*"My name...", "What I do...", "Who made me..." and one random short sentence.
**The order can change but its 3 bluntly short sentences normally in my samples followed by one of some length. I swapped it for Prima because I wanted to put some oomph in "I am an opera singer".
**Tonio's final word is "Please let me sing" and was put in because he can sound so pitiful pleading when you use him in a certain way and I wanted to show it.
*Sample length 10-30 seconds, more closer to 10-20.
*If natural faults can be displayed, do so.
**Big Al crunches just saying "I am", Prima has "Woa-ill" and Tonio says "Sing-uh". Sonika drifts in and out of clarity and all 3 Zero-G vocals pluck. Gackpo and Kiyotery also pluck in theirs, wile Gackpo has a slight Big Al croakiness proving it wasn't just him with that problem. Wat noted this is related to the deeper sounds, Vocaloid can't handle is as someone asked him.
Other then that... have fun.