I like to see other toys as comparison. I have a million toys and it's likely that I have what's in the picture so I can easily gauge it that way. But, as far as household items, rulers are a good way to present accurate measurement. I see a lot of sharpies in images too which are pretty good, because most people have those lying around.

I don't know what's the least useful, because it really depends on the size of a toy. For my dildo reviews, I like to use bottled water and Coke cans as comparison.

I try to use a pen/highlighter for smaller toys or another toy, if it's a common toy. I tend to use the Amethyst as a comparison for my other glass dildos.

I like soda cans because they're almost all the same size. Rulers are good, too!

I like to use things that can be found all over the world. Tubes of lip chap, a Venus Razor and a tube of mascara. If I had any type of carbonated beverage in the house I'd probably use that as well as that is a standard size. Originally I was going to use a passport as those are all the same sizes, but for many months of the year it is not at home!!

I find things like pens just don't work as everyone in the world has different sizes.

I love seeing comparisons with other toys of the same type so I always include those.

I prefer to see standard items like soda cans, Bic pen, etc. Also, the pics that show a product compared to other similar toys are very helpful too.

I've used the generic yellow hi-lighter because I've seen it in so many other photos. Rulers are good to because it gives you a visual of numbers with the size. Best of all I like seeing similar products, usually I own one that I can compare it too. The worst? an eating utensil like a knife or fork, those can be any size or shape, even a No. 2 pencil if its sharpened, who knows how really long it is?

I use a ruler, and a pen. I also like to use a quarter when showing how thick something is. And against other toys if I think the comparison makes sense.

Rulers, water bottles, and other toys.

I like using common items such as a lighter, remote for satellite tv, pack of cigarettes, pop can, etc. These are usually found around the house...

I don't know that they're the most useful, but I always find the ones with (non-phallic) fruits really funny. It's like, "Hey look, it's a dildo laying next to an apple!" Or "Well, that Hitachi and that pineapple go well together, don't they?"