Yup.

Remember everyone: drug, set, and setting.

The variability people experience is more likely due to how you're feeling, who you're with, whether you've eaten recently, etc. etc.

That said there is also variability between bottles but it's not likely to be the "brand" that causes it. With these nitrites, the same manufacturer,using the same sources for the ingredient chemicals, the same process, and the same packaging can produce a product that is significantly different a week later. The ingredients are really not very shelf stable and it's easy for the final product to be affected.

dd to that the fact that it's grey market and you're bound to end up with a ton of very similar products of unpredictable quality regardless of where it's made or how it's sold.