Definitely do bloodwork in advance for adult/older dogs or dogs that may be prone to abnormalities if anesthesia is the route. I think the size makes a difference so if your dog is smaller, go to a vet who has alot of experience with or even specializes in small animals... but I will never do sedation for teeth cleaning...only necessary dental work that can be a life or death problem. I had taken my pom to an anesthesia free teeth cleaner and it was great. Because she was a rescue and abnormally small (which we all know the dreaded "teacups" bring about a slew of problems, which seems to always include bad teeth on all my tiny rescues vs the normal sized toys), she dropped a tooth. I took a chance and took her in for cleaning and extractions that needed sedation. After going into cardiac arrest, they were unable to restart her heart so I've vowed to never have one of my pets put under basic cleaning since then. Unfortunately, we dont have an anesthesia free cleaning in the area we're in now, but dahlia's on a raw food diet which includes raw meaty bones, so her teeth have remained pearly white and healthy. Wish I knew this before. I do keep them checked though, and if she ever needs tartar cleaning, I'd drive the distance for one.
When I had dahlia spayed, she needed sedation (obviously), so I had bloodwork done at the same time. She had one done months before the procedure, so I already knew she had no heart/vascular problems before we got her but thought I'd have a more thorough one done with my vet also so why not while she's asleep. Although she had good results otherwise, the bloodwork showed higher levels of stress from the anesthesia... which was a relief since that one elevated level could have meant a life threatening disease (I cant remember what now). I don't mean to scare anyone since sedation is absolutely necessary in alot of cases and the chance of passing is still rare, through personal experience I still won't do it if there are alternative methods since I haven't heard of a mishap like this yet by doing it this way.