Do you have an alt account for dumping trash?

Hum, nope.
Instead, I give them on the Steamgifts forum. some people will gladly take them, and they don't go to waste.

Unless it's coupons. Then, I dump them to Trashbot.

I have a list of friends I give my stuff too. I also trade things away or do random giveaways. I have a huge list (~250) of unused keys atm.

I have an alt account, yes

I've dumped mostly bundle games on it. My family uses it quite a bit though, including right now.

I only created one 2 years ago cause I wanted to try out the cracked Steam client :p

Nah, i'm so lazy to do that :P

I have steamgifts for that purpose :D
Don't really have any bgrounds/emoticons left, already did big stuff giveaway few months ago.
Almost all duplicate games go to sg giveawaus as well

I do have an Alt to store my Tf2 Crates and get more drops.

My alt is used by my son, and probably has a few hundred dollars worth of games...if we don't count bundle/sale prices.
It is also my garbage dump

For everyone who reads this and just dumps coupons, I figured I'd mention that a few kind people set up a group where people can post coupons they don't want and donate to people who might want them.

Valve says I shouldn't create alts, so I don't. I like my library too much.

That's not to say I keep trash. I have Trashbot for taking it off my hands.

Don't really need one... Got plenty of unused keys that will end either in friends library, in random people ones here, dumped in chats or traded. Coupons generally end in Trashbot inventory, or I'm just waiting for them to disappear :p

Why would I bother with a second account when I can do everything I want on my one and only acc?
I like to collect emoticons&backgrounds and if there's anything I don't want in my inventory, I can easily give it to a friend or trade it to a bot.

I have made alt account rather to redeem free promo games there, and as an experiment, how many games I can get without spending a cent. Not so long ago however, so I have only 5 games so far.

If that thing has a price no matter how shitty is it... I'll trade it to someone

Yes, and i also use my alt account to go to trading sites that are well known to be festered with trollers/bots that add and link you to some phishy website, and using that spare as a sort of shield and keep my friends list and inventory clean and free of clutter.

I have an alt account, used it to get more drops on tf2 years ago, but I don't really dump anything in there nor use it :o