So when you say nasty I assume the previous owner used a
juice not to your liking? Or are they physically dirty? For smells you can put them in a bag with coffee for a few days.
I also follow that up with a stay with some baking soda.
Also flavors tend to stay in the bottles and especially the O rings Might have to chunk those.
After all that Howards Wax and feed all over the inside with a QTip. Then some hard wax in an appropriate color. A cape cod polishing cloth on the brass cup and she's like new.
Sometimes it is needed to replace the tubing. You can send it in or order the replacement parts on the website and do it your self.