English uses the word Dutch to refer to language and people from Holland or the Netherlands. The English word used to include people from Holland and the Germans who the English came in contact with in the 17th c. The correct name is Nederland. Holland is only two western provinces. The language Nederlands is also an official language in Belgium, spoken by over half of the population there, some 6 million people.
Although this word is the same as German "Deutsch" the mother country and the Dutch word "Duits" means "German", "Duitsland" is "Germany" both words go back to the ig. teuta: "people, folk". This might explain the German saying "auf gut Deutsch": in plain English or "mit jdm deutsch reden "to speak bluntly with sb. People in Holland are still very sensitive to anything which is Deutsch perhaps because of the history or neighbourhood or both. Generally speaking the Germans are friendlier to their little neighbouring sister.
Now surprisingly lots of things which are negative in English are referred to as Dutch since they apparently, date back only to the wars in the 17th century. In addition competition played a role in painting such a negative picture. The two nations were rivals as seafaring and neighbouring nations. However most of such expression are no more in use or are not known:
Go Dutch: split the bill (the Dutch being stingy) but the Dutch refer to "going Dutch" as "having an American party". Splitting the bill is a very common practice in the Netherlands. This perhaps shows how the Dutch feel about this matter taking into consideration the English dominance internationally. Dutch treat or Dutch lunch is the same as go Dutch in that each person contributes his/her own share. The /d/ in Dutch in this meaning can also be written in the lower case.
Dutch courage: false courage gained through drinking alcohol.
Dutch books refers to doing people out of money by using mathematical tricks. It is said that the English write the sound [f] in with a /gh/ and not an /f/ because those people who were in charge of printing were Dutch and they were paid by letters. The Dutch of course wanted to earn more money so they chose /gh/ instead of /f/. The /gh/ way of writing on the other hand is related to the Dutch sound [ch]. After all German has nearly the same sound and it still is, in Scots dialects of English. (Or else, the sound occurs in other words with such spellings). /Gh/ often occurs in old spellings, mostly in names. However, It is said the Dutch were responsible for the /gh/ in and not for the /gh/ in etc. Many of those printers were in fact Flemish and much English printing was done in the Netherlands through the reign of Elizabeth, because of the intense censorship. The [gh] sound was pronounced in England until the Norman invasion and their confusion of a letter with /g/.
OED lists a lot of other expressions where the word is characteristic of or attributed to the Dutch often with a derisive application, often with an allusion to the drinking habits ascribed to the Dutch or the broad heavy figures attributed to the Netherlanders or to their fat-bottomed vessels. Sometimes foreign or un-English:
Beat the Dutch: do something extraordinary or beat everything
Do a DutchL: escape, run away
Double Dutch: a language that you don’t understand, gibberish nowadays replaced by Chinese
Dutch bargain: cheat
Dutch comfort / consolation: whatever ill happens to you there is always somebody that’s worse.
Dutch pump: a punishment for those prisoners who were drowned if they wouldn’t pump hard
Dutch treat / lunch: see go Dutch
Dutch wife: is known in Japan as a kind of life-size mechanical doll with built-in electric heating to liberate men from dependence on opposite sex.
In Dutch: in disgrace
Sometimes the word Dutch in English simply reflects Dutch excellence in painting like Dutch school: a school of painters, gardening, and making tiles or to South African Dutch. No intention to hurt Dutch friends is intended.