I recently commissioned some art from a very talented artist (Name withheld because it's not relevant), and I absolutely loved the way they drew my fursona. However, there was a slight problem with my colors being off in a couple places. The artist said they went off of my ref sheet, but still somehow managed to miss colors in a few places. It's not a very big deal, but to me, someone getting my colors wrong is akin to mispronouncing my name- it's like a pet peeve.
Instead of being one of those whiny commissioners that insists the artist gets every detail just so, I usually take the file and make the minor adjustments myself to the colors as needed. This serves to both lower the workload on the artist so they can take on other commissions, and gives me art practice while perfecting the look of my fursona. To me, that's a win-win. With the first piece I ever got commissioned, for example, I adjusted the eye color until I found a shade I liked. The most common error is that the artist uses a medium-dark gray for my fursona's black fur, when his fur is supposed to be a jet black, so I'll go back and darken the color to a very dark gray or straight black, depending on whether or not it will hide line art. Another alteration I've made is recoloring my paws and the underside of my tail to a silver color as shown in my reference, instead of white. When working on the piece, I take great care not to alter the quality of the artwork, and do my best to make it look as if it was never altered to begin with (the only exception being my reference sheet, because the original file is lost to Oblivion, and it's almost impossible to recolor a jpeg image cleanly). In the end, I have a greater appreciation for the image, because it looks just the way I imagine my fursona to look, drawn in the style of one of my favorite artists.
Now, the advice I need is in regards to the actual editing of the images. When I spoke to the artist about it, the artist told me they found it very disrespectful to alter their artwork, and asked me not to. Other artists I've spoken to say that it's my right to edit the art, because they didn't get my colors right, and I paid for the artwork.
I'm pretty sure that by paying for the commission, I have certain rights to the image, and because it's my character, I own the rights to his design, and I should be free to make the necessary alterations to reflect my character's design. However, I don't want to disrespect the artist, even though they made a few small errors in my commission. So I ask, what are the things commissioners can and cannot do in this kind of situation?
EDIT: Since it seems that some are speculating on the specifics of my particular case, the image in question was a digital file, flat colors, no background, and I did not see any WIP images before it was finished and posted, if that clears up anything. However, I intended this to be a more generalized question about what a commissioner should do in the event that they find the final product misses key design aspects of the commissioned character, such as leaving out a color entirely, which has occurred multiple times. Though it seems like the final answer is "Your results may vary" based on the artist you commission, since some artists find it disrespectful to make alterations to their work, but others can be offended if you ask for changes to be made after it's been completed. The secondary question was the extent of the rights of a commissioner of the artwork they purchase, and whether or not they would be within their rights to alter an image in a way that would not violate the artists' moral rights, but it seems there's no clear answer for this.
EDIT 2: Another issue that arises is the fact that an artist may charge extra for changes, when a client paid for something to be a certain way when they originally commissioned the artist. When the artist has made an error, but is requiring additional payment to fix the error, what should a commissioner do?
EDIT 3: Alrighty, I think that about covers all the questions I had. Thank you all for providing a wealth of useful information! Hopefully others will find this topic useful as well, and both artists and commissioners can find common ground without anyone stepping on the others' toes. ^^