Wife wants to buy essential oils for health reasons. Scam or no?

Do some essential oils have biological activity and do something? Yes.

Should you or your wife forego any normal medicines or treatments because she wants to buy essential oils? Absolutely not. Nope, nope, nope.

Treat them like aromatherapy and calming incense and do not expect anything else, even if they might actually do something else.

Peppermint Oil seems to help my headaches.

Some of them have quite good evidence behind them, some don't. I would aim to get good quality oils that have been stored well (glass). Emu oil has good evidence behind it, but the smell was too off-putting for me.

Evidence supporting what exactly?

"People use emu oil for conditions such as high cholesterol, dry skin, wound healing, sore muscles, and other conditions, but there is no good scientific evidence to support these uses."

You essential [snake] oil people need to start looking into info sources other than word of mouth from your supplier and fellow salesmen. If you hear something all the time from everyone around you, it starts to sound true.

If you have 1000 leaches on your body, I’d get that checked out quickly.

1000 leeches OTOH, maybe that’s too many. Therapeutic dose is 100.

Olive oil tastes good in pasta or on bread and is good for keeping your pasta from getting to sticky.

Coconut oil is my favorite for cooking popcorn because I like the slightly sweet flavor it adds.

I think there are some concerns with Canola and Vegetable oils

My Mechanic keeps telling me I need to put motor oil in my car to keep it from blowing up, but my doterra rep sells essential oils and that's not one of them so my mechanic can just shut his mouth. He's probably not even a platinum level doterra supplier so what does he know.

Things like tea tree, not sure if it's an essential oil but oregano oil has quite strong anti-bacterial effects that in fairly decent studies have been effective against certain forms of infection. Obviously they are not a cure all at all but that doesn't mean ALL of them should be discounted. I also don't see why you'd need more than a few. Also depends what you're using it for - obviously it's not going to cure a broken leg for example.

A huge amount of modern medicines are originally from plants or things like fungi so I wouldn't be so quick to discount something natural. They obviously can have potent effects on the body. Look at things like foxgloves, cyanide etc.

Also if things like the latex from the poppy pod can have such strong effects it's not ridiculous to think that some plant oils can have an effect on the body. Oh, but it's only a little plant etc.