The handler/trainer always has to be aware of all the scents a source may be presenting to the dog. I know a dog handler that has a massive collection of animal bones to proof with. When I visited the handler's home, I noticed all the animal bones were stored right next to the human remains freezer. I convinced the handler to toss all those animal bones and I'm pretty sure the dogs proofed off those bones were in conflict. Dried bones will absorb most scents in their vicinity and hold them for a long time unless cleaned properly with distilled water and heat. Even then I use new dogs(set up a blind where a dog team unfamiliar with the scent is asked to work an area) to show me if a source or proofing source is as it should be.
A seminar I used to teach at requested I set up a problem that I had set up one year on a whim. I called it "handler hell." I went to multiple stores and got all the containers I'd ever seen handlers use, these being blanks. I collected road kill for two weeks. I then went tot he local butcher and got routine meat sources. I set up handler hell with all the gotchas I've ever seen other handlers get burned on or ignore. I first place two real human remains sources in the area, one being bone and one being decomp with a good distance between them. I then start tossing distractions all over the area. I had one instructor tell me at the end of the seminar that I'd forgotten to collect "that scented puppy tennis ball in the hanging suet cage that his dog had just alerted on when every one was done." I told him to keep it as it was a clean blank for the dogs that are tennis ball crazy. That instructor will remain nameless.
I have all the handlers that wish to work it come with me at the beginning. I hand them each two flags that they can put their names on if they wish or mark such that they know which one is theirs. I inform them all that there are only two valid human remains sources in the area. I instruct them that they can watch each other if they wish (or not). If someone wants to work alone, the others should respect that and turn to face the other way while they are working. I then proceed to go set up other problems, leaving them all to it. It's always produced interesting results. One year I had some really nasty beef fat that had sat in a jar out in the sun for a year.....turned out to be attractive to some of the dogs. Some dogs have alerted on fresh beef tongue wrapped in a clean white towel and placed in a suet cage, the blood showing on the towel. .....is it the dogs or is it the handlers....I don't care.... they flagged it, they'd have flagged it on a real search.
Each subsequent year the students requested I set up another. I've used McDonalds burgers in plain site in a suet cage at 8 feet up and had handlers talk themselves into it, suggesting I'd just be plain evil and put a human source under it..........?why would I need to be so evil? ....As the Shadow used to say (yea, really aging myself now....) "What evil lies in the hearts of "handlers"?" Handlers do it to themselves and then torture their poor dogs. If a dog alerts on latex, it's the handler's fault.
When everyone is done, I show them the location of the two valid sources. I let them come to their own conclusions. There will always be the handler that flagged something three feet away that will convince him/herself that the dog was on the right scent, but tagged the wrong thing.....happens all the time in real life if you've ever had to search a suburban homeless jungle or back alley. oh oh, I did offer to set this up one year behind a local Burger King....they decided that was too much. One year I had a handler come to me while I'm setting up the other problems and ask me if it's ok if she uses more flags. I looked at her and said, "you understand there are only TWO valid sources?" She nodded, almost in tears, but stated that she had to know all the bad things she'd taught her dog to alert on. I'm easy with those into self-torture and told her to go crazy. She planted a total of 10 flags.....
I have had this done to me and I've done it to others. Buy a new box of latex gloves. Spread all but one of them evenly out over a meadow on a nice calm day.....put some of them on your hands (clean, no cuts) and turn them inside out and toss them down. Take one clean glove and handle a wet human remains source with it. My favorite is a little adipose tissue, clear but strong scent. Turn the glove inside out. Toss that glove out in the middle of the others. Have the handlers find the right glove..... As the dog teams improve, begin cutting down the overlap space between the gloves. ....I'm thinking two feet apart from each glove is fair.
As much work as these can be to set up, they have to be done on a regular basis as our dogs, just like us, get fat, dumb, and happy with routine. If the handler always sets out five sources and decides one day to set out only four, I can almost guarantee you that the dog will find a fifth something to alert on....it might be valid in the dog's mind as it was downwind of a really stinky source and made a good visual...still not right....believe me, I get burned with my dogs just as much as everyone else does. Recently, worked burieds where one handler had their dog dig in every possible buried spot to check, you are guaranteed that some of the blanks will become contaminated. Does that make an alert on a blank any more valid? Unfortunately, no. Can I as a handler understand it? Yes, but can't fault the dog. Just means more scenario work to bombproof off of other handlers because we often have to follow other dog teams on high profile searches. It means my dog might have to go back and forth between holes to compare. It means I might not call them right away and work the dog from multiple directions....I know I've frustrated some evaluators doing that, but when I don't I might fail.
As to the original source of this part of the discussion. While I've worked embalmed graves, I won't train on embalmed remains. One of the doctors of the Body Farm (after Bill Bass left) told me that embalming holds for a decade or two then our bodies quickly liquefy. The scent will have both components of human remains and embalming fluid in there, but I only want the dog to pay attention to the human part. I'm not sure if I'd proof off of embalmed remains though. I think that might put the dog in conflict. Knowing a lot of embalmers, I know that there are variations in embalming. The cadavers that are used for gross anatomy classes get a more thorough embalming than most funeral homes provide and I'm sure there are some embalmers that are more thorough than others. Working for an M.E., I could never ask a funeral home for any remains as that would present a conflict of interest and a betrayal of trust on my part.
I've got cremains as well, but rarely train on them. I'd prefer to use charred remains. The dog can find them, but I've never had a need to work a search where the training was required.
Oh well, enough tangents.
Jim Delbridge