y'all able to tell 1966 is my favorite Topps set? Here's a 1961, #6 Ed Roebuck. Red printing splotch above the "k" in Roebuck, on his jersey. Only seen one other like this, though I haven't scoured that closely as I already have a copy. Certainly an uncommon one.

Here's an easier '61. Alex Grammas, card 64, with or without a black dot on back of his neck. The black dot is tougher than the regular card but this is an easy one, maybe 25% or so have it. Easily bought cheap on comc.

And another really easy 1961 Topps. Bill Henry #66 is found with or without a red pixel in the grass, in the bottom right by his pant leg.

The red dot variation is on maybe 35% of cards.

And this one is even easier! Joe Pignatano, #74. Note the 'crack' line running from the right hand border across the card to his elbow.

I think this card is found with this 'crack' in it about 50% of the time. Tons of them to choose from.

#75 Lindy Shows Larry. Finding pigmentation differences in common on every vintage Topps card, but this one seems to really exceed what is normal. The card can be found with both mens' pants white and light faces, or glowing red faces red pants, and red grass. Looking at my copies, I think this is more than the result of cards coming out bright or light depending on the ink levels used when the sheet was printed. Some of the red spots really shouldn't have red there in any amount, and don't on the 'correct' copies of the card. This is not a rare one to find at all, pretty easy recurring defect if this meets ones definition.

EDIT - my iPhone has a hard time picking this up, you can see it in the photo but it is truly blindingly obvious if you have both cards in person

1961 Topps series 1 again. 83 Bob Bruce has a red spot on jersey near his neck. Maybe 10% of the cards have it? Not too tough

Possible variants, I have not encountered a corrected copy of these defects, but thought I should note them as there may well be variants here in your guys collections:

1961 Topps #115 Johnny Antonelli - red dot by ear, right side.
1965 Topps Manny Mota - white splotch interrupting part of ".259" in lifetime batting average.
1966 Topps #120 Harmon Killebrew - stray blue line by ear

1961 Topps 137 Chuck Dressen - big yellow splotch in red banner. Topps sure seemed to struggle with random yellow ink getting into places it shouldn't for a good 30 years or so. This one is very, very tough to find.

The lines through his face from the frame are pencil marks, not part of the printing

And speaking of 1961 Topps and yellow problems, here's another toughie. 159 Orioles Team card, with yellow streak in name box

The other arrow is pointing to a white splotch above one of the players heads. It is difficult to see, even in person, and its hard for me to tell how recurring or rare this is as my eyes have a tough time here on scans.

1961 Topps card 178, Bob Nieman. With or without a blue splotch in the sky next to his ear. This version with the blue splotch is less common, I think maybe 5% or so.