Orcish is gutteral and choppy. It is made up of a mix of long vowels and hard consonants. A variety of clicks, pops and squeaks serve much the same function as punctuation are used instead of inflection to give context.
Orcish doesn’t lend itself to subtlety or subterfuge, in fact it is difficult just to speak it quietly. It lacks the vocabulary for concepts for things like non-martial art, romantic love, or beauty. This does not mean that Orcs don’t create magnificent works of art, fall in love or feel overcome by a magnificent sunset, it just means that they have a hard time expressing those things. If an Orc really needs to express a concept that Orcish doesn’t cover, they borrow a word from another language.
Even without tusks, it is impossible to pronounce properly without spitting or drooling, which is not considered impolite in Orc society. Visitors who visibly try to avoid spitting while they talk is looked at as strange and prudish, and individuals who don’t spit while they talk lose respect and are seen as weak.
Sounds like Swahili spoken with a severe underbite by a 3-pack-a-day smoker.
The different dialects of Orcish really only differ in pronunciation and accent.
The written form of Orcish consists of crude pictographs. There is no phonetic written language.
These pictographs vary wildly between the three main dialects, but are simple enough to get a basic understanding even if the reader doesn’t know Orcish at all.1
1 Intelligence or Linguistics: DC 15 (basic meaning); DC 20 (explicit meaning)