There's no visual indication on the wall itself, but rather on the map. A secret room is always connected to at least two rooms, preferrably three, and it prefers to be connected to the shop (though that isn't 100% true). If you see an empty space connected to three rooms, the first thing to check is that the connecting walls in each of the three rooms actually have walkable ground. If one of the rooms has a pit or block where the entrance would be, that's not the secret room.
Super secret room does the opposite: it will only be connected to the map in such a way that it does not touch any other room but the one that has the entrance. Like the regular secret room is generally as close to the shop as it can be, the super secret is generally as close to the boss room as it can be (often in the room right before the boss).
Keep in mind that the first floor has slightly different logic so as to not make the secrets too easy to find, and as such isn't a good floor for you to practice on. Every floor after that will use the logic I described above. Also keep in mind that secrets are your secondary use for bombs, the primary use is to blow up so-called tinted rocks. They're rocks marked with an X and, on every floor except the Womb and Sheol, are a different color than other rocks. They contain goodies you want more than the coins generally available in a secret room.
Good tips! I totally ignored secret rooms for a long time and have been using them recently, they make a huge difference. I went from never opening a shop to buying minimum two items per run. I didn't know about the super secret rooms, found a couple on my last run that helped a lot.
What exactly are these tinted rocks? I kept an eye out for them on my last run and didn't see any. And what do they drop? Hard to believe it could be better than the potential black and white hearts in the secret rooms.
I just had an amazing run, I was about to put my Vita away and decided to do one last run. I got Guppy's Head (I think, whatever the nine lives one is) in a devil room early on. I usually pass on that, but I figured why not. After that I got double shot, got extremely lucky and got three Tear Up pills, and a few damage-ups. I got an HP-up and a few silver hearts, but died to Mom. I then amazed myself by killing Mom with only 1 heart.
On the way to
I got Guppy's Paw and Tail, making it the first time I've ever been Guppy. That ended up being every bit as powerful as I've been lead to believe, I absolutely destroyed the boss in a few seconds.
I love this game so much, I've been playing it almost daily since it came out and still feel like I have a lot to learn. These tinted rocks for one, but I feel like my general lack of knowledge still hurts me a lot. For example, I don't get to Mom every time, but basically every time I manage to kill Mom I get the Boss Rush room. The problem is that I don't know all of the items well enough to know if any of them are worth it most of the time. I did the Boss Rush tonight and one of the options was an item I'd never seen before. Turned out it was Spelunker's Hat, which didn't end up being worth the trouble to get.
Anyway, thanks for the tips, I don't post often because I don't really have anything to add but reading this thread helps a lot.
