wiki vandalism

So-called wiki vandalism is the reduction in usefulness of pages by insertion of errors, misspellings, "American English" and so on. It is often just called vandalism by frequent users, which is a poor practice:

In this conceptual metaphor, it is likened to the smashing of windows or smearing of paint on walls, which reduces the price of infrastructural capital. But it is only instructional capital that is being "reduced in value", which is a different type of capital asset entirely.

When commercial POV is involved, wiki vandalism is usually called spam and dealt with much more summarily.