One of the hardest things to judge when reviewing a text for publication is the appropriate nature and quantity of any humour. It may be a fairly simple task in standard technical writing, where the clear expression of facts and instructions takes priority and humour tends to get in the way. In such cases, humour is almost automatically deleted.
However, there is a cline in the application of humour, culminating in a text that is explicitly and intentionally funny or satirical. When humour is included, any textual alteration needs to be very carefully considered in context. An apparently simple spelling 'mistake' may be a deliberate pun, even if the reviewer considers it to be a poor one.
Furthermore, there are questions of cultural appropriacy, including whether readers will find material offensive or maybe just won't have the background knowledge to get the joke.
In addition, the target group of a text may get a buzz from the delicate flavours of semantic sophistication or may prefer the rare-done red meat of outright mockery. Maybe only the writer knows which crowd is the real intended readership and how they like their comedy served.
In the middle reaches of the humour cline lie any number of text types, from press releases to theatre reviews to literary fiction. (And good luck, by the way, to those fine people embarking on NaNoWriMo, National Novel Writing Month, at this time.)
One of the challenges for a sensitive reviewer in all such cases is not to confuse linguistic correction with censorship of content. The chief editor at a newspaper may be entitled to wield the censor's pen over journalistic copy, but it does not follow that a proofreader has the same right to make such a call.
To make that distinction between language and content, a high degree of linguistic and cultural awareness is required. A lot of this awareness grows through writing. Editors who don't also write, edit at your peril!