Sans Serif typefaces were originally called grotesque typefaces by alarmed typographers because they dispensed with these little flourishes in favour of a cleaner, blockier style, more appropriate to the mechanical nature of the printing press and a stylistic denial of the ornate lettering that was the legacy of handwritten books. It was sort of like what happened to painting after photography came along - new technologies freeing artists to pursue a new way of seeing their art. In recent times, the precision of computers has inspired an even more extreme backlash, and there is a whole new style known as distressed type. Favoured by hip magazines for young people, these raw, ragged and reticulated types have alarmed a recently matured generation of typographers who have not stopped at the word grotesque in their descriptions of them. Think of the typestyles available to you for use in your documents as a palette of colour and apply it with taste and restraint.
Some simple rules follow.
Never use more than two or three typefaces in a single document and strive to never have more than two on the same page. When you use a typeface, use the italic designed for it. Don't choose another italic arbitrarily. Restrain italics to words you wish to emphasise, captions for pictures or call out copy blocks. Italics are extremely difficult to read, but judiciously used, their ornate curves can make a page quite attractive.