Times when a hero is straight-up useless?

Expatriette with all guns and no ammo or vice-versa. Unity with all bots and no equipment or vice-versa. The Adept if he (somehow) ends up with all instruments and no songs. Any heroes who can only deal Melée and Projectile damage (eg Legacy, or Haka in a no-target environment) versus Shu.

Expat with all guns and no ammo is a fine start.  Play a gun and start shooting.  It’s when you start with all ammo in hand that you don’t have much to do since Ammo can’t be played for any benefit in advance of having a gun.  

I often don't even bother playing ammo. They're basically like one-shots that add a little bit of damage or damage reduction, far weaker than other heroes' comparable one-shots and mostly worse than her own other cards. But I fail to draw any guns with her pretty often. Slightly less often, BoT Chrono-Ranger with no useful bounties or guns (who is rubbish), AZ with no modules (even worse), or Mr. Fixer with only tools or only styles (not useless but really weak). I rarely get AA with a useless card combination, but it does happen. I've never had a problem with Unity given the amount of card draw she gets.

AZ with no modules or a way to get his modules at start of game is a bummer but he can still contribute through hs card plays.  It moreso means that unless you’re F6/F5 AZ you won’t be using the base power.  Mostly it means you aren’t getting the maximum potential out of his damaging one shots. He also has ways to contribute through his Ongoings.  

Oh yeah, bit of a derpy moment there - of course Expatriette is useful with guns. Derp. But the rest was right ;).

All-projectile and -melee damage heroes can also run into trouble against Omnitron and Grand Warlord Voss.

You can easily put together a team with no Ongoing destruction, which is problems against some villains.

My friend ended up seeing no damaging cards once Spite filpped.  Just deck manipuliation.

That was not fun for him.

I respectfully disagree here. If you play and use her ammo one at a time, then yes, they are like very weak oneshots. 

A lot of Expat's strategy comes from building up to a big turn. (Think a more serious Guise).  You are going to want to keep playing guns and loading ammo until you can get an unload. Speed loading helps you to replay ammo if you either need an immediate effect or dont have much else to do, but you shouldnt hit a standstill and only play then use ammo unless you are not drawing anything else, and at that point pleanty of other heroes would feel useless , so it's unfair to think of that as a uniquely Expat problem.

All I know is that Hollow Points + Submachinegun + Aim (with a timely Reveal The Flaws) turned an overwhelming Infinitor board into paste for us last time we played against him and made the rest of the game much easier.

Nearly every hero against the front side of Miss Information...

Mr. Fixer with 0 tools in hand to start, and not seeing at least a tool box for 4 rounds.

I think the video game put me into that hell recently in a one-shot. Never occured to me on my inevitable second attempt to shuffle his deck early. Anywho, back on topic.

Thats probably the worst situation I've ever been in playing a hero.

Tachyon in the recent Heretic one-shot - 1hp damage attacks when every villain target has 2 our more points reduction makes for a very frustrated Tachyon!

Mr FIxer isn't useless without Tools...he still has Styles and can still punch stuff via Strike and erm...the One-Shot that deals two damage whose name I've just gone blank on...

Charge!

Is it just called "Charge"? I figured it had that word in the name somewhere but kept coming up with "Charged Attacks" which is Ambuscade's :P. Apparently I was thinking the name was longer than it actually was :D.

Legacy, Parse, and Wraith vs the Ennead in Rook City.  Better hope that Shu doesn't come out...

Or Megaopolis