I'm self taught, been shooting for roughly 3-4 years.  I'm a Youtube warrior for now, and have been, as far as learning techniques.  Here's my situation though and from YouTube you can never really tell what level of accuracy you should expect since they usually use bench rests, match ammo, etc.

1)  I buy milsurp weapons.  My rifles are: Mosin, Mosin M44, Norinco SKS Carbine, AES-10B.  None of which are light and/or well balanced weapons like an AR platform would be, so that doesn't help.
2)  Mosins get Milsurp ammo cans.  SKS and AES-10B get Tula ammo

At 25 yards (since the range I usually go to is indoors, Outdoor ranges are like an hour drive for me), what kind of accuracy should I expect:

1) Off Hand (90% of the shooting I do it standing)
2) Bench rest, basically just putting the gun on the bench at the range.  No stabilizing vice, etc.

It's always been a mystery for me, am I doing good?  Do I suck?  I have no idea based on YouTube.

I can usually get in or near the bullseye on standard indoor range target paper (I haven't shot since November due to the holidays so I don't have anything to show you right now).  The AES-10B is the exception just because of the front end weight it's very difficult to hold steady, but I can still get in and near the bullseye at 25 yards.

Too many "what's" to give an answer.  Not the best firearms or ammo to gauge your ability IMO.  On the other hand... have someone shoot your goods and see how they do compared to what you can do.  Where in FL are you?

Yeah that's what I wondered too, it would be nice to have a somewhat 'professional' test them out to see how it goes.  I'm in Orlando.

How big is the bullseye?

Yeah the targets have a 2" bullseye.  With most guns I can get in or right around it so I wasn't sure if that was good or not (the right around it part).  Seems like everyone on Youtube is upset if they shoot a 2" group at 100 yards, so it's hard to tell what's a realistic expectation and what's not.

Seek formal training.

I'd look at it like this, if I were you. Say to yourself 'I don't know shit, and need some help from people that do.'

Then seek out true professionals to teach you. Go into it with all your past habbits abandonned (no loyalty or desire to stick with 'how you've always done it')

You should have no problem then. Admitting you suck is half the battle. Even if it turns out you don't really suck that much, don't go in thinking you know your stuff.

EDIT: I sort of mixed up your actual question. Kinda, but in a way I have the same answer. With some training, you'll shoot and know your capabilities better. If you're in a training course with others, the instructors will know what to look for during each stage of fire and coach you if they see your results aren't great.

CavScout:

I totally agree, training is kind of expensive and the only reason why I haven't done it yet.  One of the problems also is that places like Gander Mountain that we have here in Orlando seem to train on handguns and don't do rifle training.  I haven't called but maybe they could train on rifles if I buy a handgun training package.  Otherwise the only other training are those tactical training classes which are like $3-400.

Other than that I have no issues saying that I suck and learning something completely new.

 

Here's some goals to shoot for with no bench rest.
- Head shot (3x5" card) from 25 yards offhand in 1.5 seconds (manage your holdover)
- Double tap to body (8" paper plate) from 50 yards in 2 seconds
- Rapid transition to sitting/kneleling/prone and shots to 8" target at 100 yards in a few seconds (varies by position)
- Slow offhand shots at 100 yards - try to get 10 shots in 2 min, and see how many you can get on a paper plate (par is 8/10)

These are very tough standards for an average carbine shooter, but this is what you might be able to accomplish after a week at someplace like Gunsite.

Yes, the training is expensive, but you will probably learn more from one immersive 5 day training course than several years of "plinking"

Go to an Appleseed shoot.  Best basic training per $ you'll find.  They'll teach you fundamentals of rifle plus some history.  Won't cost very much and you'll shoot 400 rounds over 2 days.

Appleseedinfo.org

These are the ones that CSAT uses.  It is a good functional test of your capability.
http://www.combatshootingandtactics.com/standards.htm

TRI RIFLE STANDARDS SEPT 2010

The enclosed drills are designed with three purposes in mind:

A measurable standard to maintain.

An efficient stair-stepped workout program that covers all the bases.
To test the individual shooter at various times to show areas needing improvement.

1. Ready 1 shot 1 target 7 yards 1.00 sec.

2. Ready 2 shots 1 target 7 yards 1.50 sec.

3. Ready 5/1 Shots 1 target 7 yards 3.00 sec.

4. Ready 2 shots /2 targets 7 yards 3.00 sec.

5. Ready 1 Rifle /1 Pistol 7 yards 3.25 sec

6. Ready** 5 shots /1 target 100 yards/prone 20 sec. *

7. Ready** 5 shots /1 target 75 yards/kneel 20 sec. *

8. Ready** 5 shots /1 target 50 yards/kneel 20 sec.*

9. Ready** 5 shots/1 target 25 yards/stand 8 sec.


Total: 34 Rounds Rifle/1 Pistol

-All rounds must be accounted for on the CSAT Target.

-Student must pass 8 of 10 drills to be successful.

-Drill 5, one shot from rifle is fired and then transition to pistol. Must both be hit.

* 4 of 5 rounds must be in box

** Requires only a full caliber hit on target to receive a “GO”

25 yards is pretty close.  From a bench, those guns should group no worse than 2" extreme spread in 5 shots.  That roughly (very roughly, since 25 yards isn't even stabilized yet) means 8" groups at 100 yards.  That's shit, but you're describing some pretty cheap guns shooting some pretty cheap ammo.  You should strive for 1" at 25 yards, but 4 MOA is about as good as those guns will achieve.

When you are shooting offhand, you should expect to be able to hit a paper plate at 25 yards very easily.  Really, you should be able to hit a water bottle pretty much every shot.