What is really the best way to get rid of hyperpigmentation/dark spots caused by sun damage (or acne)? None of the many low- to mid-priced over-the-counter products that I've tried have lightened the spots on my face at all, so I'm curious if there is actually an effective and affordable product out there.

The most important thing is to address the cause of hyperpigmentation in the first place. Because unless you do that, you’ll never catch up enough to see results. In your case, make sure the acne is under control and you are sun-protecting well. If you are doing this, you will be amazed to see how much things fade with time alone over the course of six months to a year. Ingredients that target hyperpigmentation include tranexamic acid, azelaic acid, vitamin C, and hydroquinone. Patience – and making sure not to irritate the skin – are key. And if that doesn’t work, combining some products with laser treatments can be helpful.

Are pore vacuums bad for you? Will they widen your pores? Would you recommend using one?

We want the record to show clearly – and we cannot emphasise this enough – we absolutely do not recommend pore vacuums. First of all, the best-case scenario is, that is a very temporary fix. The process that led to blocked pores is not affected by the vacuum, so it's just a matter of time before they fill up again. Secondly, and more importantly, they don't have the ability to just selectively suck out the pores. They suck the whole skin (which can be very traumatising) and damage the skin barrier, leading to redness and bruising.

Why is the skin in my armpits darker than the rest of my skin? And why is it bumpy textured?

Your underarms have unique skin; they have sweat glands and hair follicles which contribute to this bumpy textured appearance. It is also very common to have a darker shade of skin there. This is because of skin friction, where the two components of your underarm come into contact, as well as micro inflammation from shaving and deodorant. Darker armpits are usually totally normal but in some cases can be a sign of underlying disease, such as diabetes. If it is very prominent, it can be helpful to have a doctor check them out.