Berefootsies and Roald have come up with a very good point. A lot of people don't like dialogue. Not everybody likes leg fetish, so we have a mix of sites to cater for everyone. Dialogue is only to establish her as a real person and to attract the viewer. It's not required to be done all the time. But a "I'm cumming", "more", "Yes" and other things occasionally always helps. Solo Girls, can ask if the guy is watching, joining in, even "Let me see your dick", or "Let me watch you jerk off" is a great turn on.
I personally have never had sex, felt attracted to or bothered with girls who don't or can't speak. But I'm strange.
As for girls with a heavy accent and very bad English, or English speaking and not able to utter an intelligent word in front of a camera. Well that's simple to solve, send her home if the product requires her speak.
The same goes for girls who can only churn out a canned performance, freeze on video, or just plain unsuitable for the job. Because as much as the shooter has to make it fun, ultimately it's a job of work to produce a product for people to sell and customers to enjoy.
In England I was getting loads of girls coming for interviews for the
Astral Blue videos. Who simply didn't have what it takes to deliver a good performance. Sometimes one got through the interview and when they turned up for work, I learned I was wrong. she went home and was paid so long as she was trying.
Online many choose girls for a product that's video based, on nothing more than a few photos. go figure why shooter after shooter keeps showing us pictures of girls. When we know we sell videos.