I wouldn't, unless you definitely know you'll have someone staying with you all night, every night that you're there. Otherwise you're wasting money.
Like I say, this was only one incident, in the many, many trips I've made to Vietnam. It was back in 2014 IIRC, and in this case, I actually managed to talk the night manager out of charging me, by assuring him the guy wouldn't be staying all night - which he didn't.
Just by the way, totally off topic anyway, but interesting nevertheless.....
I wasn't planning on offing this guy. I just wanted to jam with him. He had a guitar, and I'd just bought a $90, quite functional Mandolin at one of the gift shops. We had a nice jam, and believe it or not, at the end of it he suddenly kissed me, and we started to fuck. This was a surprise to me.
Totally random shit like that always happens to me in Vietnam. That's why I love the place.