I would like to know if the use of "skinned" or "custom" dropdowns is seen to be bad UX or not?
I am aware that notable successful online retailers (who carry out Hallway Usability testing), do not employ the use of skinned dropdowns as they do not look or feel like conventional dropdowns. I have also had a suggestion from a Senior UX developer that having "pretty" dropdowns on your website will not make or break the decision whether or not a potential customer makes a purchase on your site.
From a maintenance point of view I believe them to be a major headache as I have found you can quite easily spend hours of development time on something that adds little value to your checkout process or UX (IMHO).
This is an example of a dropdown that I have at the moment.