Off-screen vamp dusting fails in Angel

[Drago]

Anybody notice how sometimes in Angel they'll stake a vampire and it won't turn to dust despite the sound effect being used (probably to save money)? If you want examples, there's the scene where Team Angel kills Elizabeth's gang in "Heartthrob" and this really bad example when they're fighting the cultist vamps in the hospital to protect Darla and Wesley kills a vampire jumping in slow-motion. This is just off the top of my head and there are probably way more instances of this.
In Buffy, it's common for them to cut away the moment a vamp is staked with the sound effect heard in the background, but they can't seem to do this on Angel. It makes it look really bad.

 

[Ethan Reigns]

Each vamp dusting was supposedly $5000 in CGI. That is why it happens. If you watch the BtVS pilot episode, a dusting appears to be four successive still shots of a disintegrating vampire. Thankfully, the producers had a graphics budget but sometimes it doesn't cover as much as they want.