Tartan has a long and colourful history, that has been known to get the odd Scot into hot-water. Due to the threat of the separatist movement in the 18th century, Tartan was prohibited by British Law in 1746. Express freedom and relaxation in comparison with rigid checked and striped patterns. Paisley is a good example of a pattern that exudes creativity and an easy-going manner, while maintaining conservative respectability. Once favoured by stand-up comedians, spots present an amalgamation of order and curves leading to a humorous effect, especially if large.
Small spots appear to evoke just a smile, which is fine.
Cats, dogs, cars, tennis rackets, vegetables, etc. are fine on weekends, making a fairly obvious statement, though often not about fashion.