Often inexperience is the cause for making untrue statements. I will list here some untruths that I have spotted online that often re-appear. None of the points I list below are valid points to dismiss a helmet out of hand.
No Cause For Panic When …
1) Your helmet has crooked decals. Many original examples have been observed with badly placed decals.
Photo courtesy of RoyA
2) The decal is not placed 3 mm under the vent hole. While official decal placement directions exist it is clear from the many helmets that survived the war that scant attention was paid to them.
3) Your helmet rivets paint seem different than the paint on the shell. I observed this mostly on M35 Kriegsmarine and M35/M40 Luftwaffe helmets , old stock and different subcontractors can be the cause of this.
Quist M40 luftwaffe – smooth painted rivet and textured paint on the shell.
4) The leather of the liner has a strange shape. Shrinking of the leather on aluminium liners can cause them to have a more squared look.
5) Your helmet has loose rivets. Used combat helmets have loose rivets , usually one , sometimes two. Three would be a cause for further inspection. Note : One loose rivet can cause the other ones to seem as if they are loose.
6) One of the rivets is missing a washer. Rivets were replaced and often in the field , although not commonly seen it’s possible one (or all) of the rivets are missing a washer.
7) Production flaws. Helmets are observed leaving the factory flawed , later war helmets will be more prone to that.
Urban Legend Alert : Scratching decals with your fingernail
This practice is often suggested by inexperienced collectors and I know I heard this way back in the nineties even. Scratch a decal with you fingernail to see if it is real. Please never try this as you can damage a nice original decal as easily as you can damage a fake. This proves nothing.