Some people generally prefer to swish the wine in their mouth like mouth wash. The main reason why they are doing it is to make the wine to touch all their taste buds which is not necessary.
The main idea behind this is to linger the wine in their mouth for a longer period so that you can take a moment to think about it. Wine tasting offer the best idea to understand the message hidden in the bottles.
Most of what we taste are perceived by our sense of smell because our taste buds are blunt instrument.
They also hold wine in their mouth to feel all the component of the wine in their mouth.
Holding wine in mouth is used to feel the complexity especially wine that are complex to feel all the multiple flavor.
To slightly warm the wine, releasing more of its flavors
While holding the wine in the mouth, it should be rolled around to fully coat the taste buds. This helps to better appreciate the wine.
The length of the finish cannot be determined until after the wine is swallowed.