"Unpleasant taste" refers to a flavor or sensation that you find displeasing or not enjoyable when eating or drinking something. It means you don't like the taste of it and may want to avoid consuming it. Full definition
It leaves a distinctly unpleasant taste in the mouth. (politics.co.uk)
The batch which was delivered to me this week was extremely sour and had very unpleasant taste. (ocado.com)
In all of its clean, natural glory unflavored protein powder may carry a slightly unpleasant taste depending on the source protein. (blog.nkdnutrition.com)