I recently purchased some heads ( Part 3626cpb0807 Minifig, Head Alien with Black Mouth and Dots on Cheeks Pattern (SW Agen Kolar) - Stud Recessed ) from Bricklink, and upon removing them from studs or torso necks, their neck base had chunks break off! These heads were new as well, not used. Anyone else have this problem?

Right, update. So I got sent 2 more replacement heads for the broken ones, AND THESE BROKE TOO. I noticed theres a weird greenish residue inside the head lining around the neck? I will post pictures soon because ONLY this head gives me this problem (and from this seller).

Seems rather odd, are these actual Lego heads, or custom jobs? Green residue seems suspicious too. Like to see the pictures, as I don't have those particular ones myself. 

They're authentic LEGO yes, not custom prints. Will have pictures tomorrow, as I need my girlfriend's iphone to take any quality photos worth a damn to see the details lol.

It does seem odd, I've never seen anything like that in any head. I've seen cracks when they are crushed through play, but they tend to crack vertically. For it to happen on replacements from the same seller too makes it sound like they are coming from a dodgy batch, that was probably dumped in bulk by lego rather than appearing in sets. Unless they have been badly stored or treated in some way. Very strange.

And here we go.

 

The heads on display as a totem. You can see the broken chunks of their necks already.

Top down view. Hell, you can see bits of plastic on the baseplate that flaked off from just separating them from the totem.

Close up from the right.

Closeup from the left.

Close up of the weird green residue that's inside the head (its been smudged around due to attempted use, but still there).

 

If anyone has any idea what this is about, I'd love to know :(

When heads get stuck on torsos people use all kinds of tools like clippers, tweezer, even pliers, to try and get the head off. And the seller has tried it here and it’s obviously gone wrong. People also use all kinds of oils to loosen the plastic so that might explain the green residue.

To me it looks like these heads were glued on, like a key chain or something and were forcibly pried off by a spastic orangutan using a rusty axe. 

The heads were removed by my sausage fingers as I bought them loose and they were bought "new" so I doubt they were removed from keychains or whatever (does Agen Kolar even have a keychain?). They WERE extremely, EXTREMELY tight however when I tried using them. Like you could hear the plastic squeak trying to slide it on and off. The crumbling of the neck however was provoked by very gentle actions and happened within the first placements of the heads onto a baseplate for displaying purposes while deciding what character to make from them. When I pulled the head totem off the plate, the neck crumbled, and when I separated the heads, their necks also crumbled. They arrived looking perfectly fine however (save for the weird green stuff).

I know this doesn't help and is small consolation but I would say they were defective from the get-go. I would certainly ask for a refund. 

If they had previously had something done to them (or were, indeed, keychains), and hadn't been properly cleaned out, then it it's very possible that trying to use them on another figure made the connection too tight, and that too much force (connecting or disconnecting) caused a break.

It's also possible there was just a bad batch.  I'd long been in the camp that marveled at how many people seem to get pieces that fracture or break easily.  It had happened to me a few times, but nothing I couldn't really explain and, having a lot of parts in my collection, I'm usually just able to move on.  However, I did have this happen to me:

This was from one of the modulars... The Fire Brigade.

All of them from the set - every single one of them.  I went to my own collection and dug out the nearly 20 I needed to complete the set, and they were all fine (so I'm not some ham-fisted gorilla, pounding LEGO into pieces).

Contacted TLG and they NEVER made good on it.  I even sent them this picture.  I don't know if the manufacturing defect was the plastic, or if it was some post process that made them just a tiny bit too small, because they were SUPER tight.

I suppose I am just unlucky then! Even a company as strict on quality as LEGO is gonna make a bad batch now and then, and we're just the one in a million to get them. Those snapped tiles are ghastly! lol