How often do you use mods(/do you use mods)?

Very rarely.

Depend on the game really, if it a game with a lot of mod. then i do use a lot of mod, but other mostly just some gameplay fix mod

Aside from Minecraft ... i dont think i used Any mod in ... years

I use mods on games that have nice mod support (Doom, Skyrim, Bethesda Games mostly) but what I really love is create mods. Can't wait for Fallout 4 mods to come out ;)

Used to play with mods plenty of times in the past but now they are called dlc and do so less often

If it's a stand alone exe, maybe. If it will affect the main game in any way, nope.
I like to experience a game the way the creators intended. If a game isn't good enough(gameplay and artstyle wise, not technicaly) in its original form I wont bother trying to fix it, I will just unistall it and play something else.

I don't use mods, they're rarely a good experience. I've been using mods years ago and I never really cared much for them since. Visual changes are pointless as you're changing the skins/textures, ruining the theme that the game had going for it and the functionality remains the same, meanwhile if you change the functionality with a mod it usually ruins any balance that the game had. Any fanmade things are usually really badly thought out, although there are exceptions. Not to mention that I wouldn't use a mod on a game unless I played through it fully already, which means that I'd end up having to replay the game to enjoy the mods and that's where balancing issues come in, where should the modded items even be? If they're at the start of the game and powerless, they'll fade out quickly, if they're at the start and powerful, you're ruining the whole game experience. There are a lot of issues with mods.

The worst thing about mods though would probably be the horrible stability in some games, like Minecraft and Fallout, if you download a bunch of mods without research, you'll end up constantly crashing the game.

At the end of the day if a mod is worth having/playing, it eventually becomes part of the game/standalone game, like some updates that brought existing mods into Minecraft or Killing floor and Dayz turning into games. Dota turned into a whole genre.