Many collectors cherrypick varieties, going through mint and proof sets or boxes of “raw” coins at shows or shops. But you can do the same with holdered coins whose labels for one reason or another do not list an attribution.
Labels from PCGS, NGC and other third-party coin grading services might not list an attribution if the company decided against the variety, if the sender neglected to pay a premium for or overlooked the variety in a submission, or if the holder predates the popularity of the variety.
One of my favorite “no attribution” label coins is the 1956 proof Franklin Half Dollar, which comes in two varieties.
Here’s a picture of an NGC label without the attribution.
Here’s a picture of an NGC label with a Type II attribution.
Here’s a picture of a PCGS old green label without the attribution.
You can do this with several coin types, not only the Franklin 1956 proof.
That year the mint decided to redesign and make clearer the left wing feathers of the perched eagle on the reverse. Type I eagles have mushy looking feathers on the left wing whereas Type II eagles have three clear feathers to the left of the perch.
You’ll have to study those feathers on the left wing carefully to get a feel for the two types. I recommend this CoinTalk article by Jason Poe who also explains Types I and II for mint state 1958 and 1959 Franklin Halves.
For the 1956 proof coin, you want to look for Type I in higher grades, from gem PR65 and up, especially in cameo or deep cameo. A PR65 Type I lists in the PCGS price guide for $60; Type II in that grade, for $35. The price jumps significantly in that grade in cameo and deep cameo to $300 and $350 respectively, in contrast to $55 and $130 for Type II.
Many cherrypickers and registry set owners like to have a cameo or deep cameo Type I and Type II in their collections, not only to showcase the varieties but also their numismatic prowess.