Professional grading — sending a card off to be authenticated and sealed in a numbered slab with a condition score — has become a reflex for a generation of collectors. The belief is that grading adds value. For a small number of cards that is true. For the great majority it is the opposite: you pay a fee, wait, and end up with a common card in expensive plastic that is worth less than it cost you to slab it. Grading is best understood as insurance, and you do not insure things that are not valuable.
What grading actually does
It does two real things: it authenticates the card against fakes and alterations, and it fixes a trusted, third-party opinion of condition so buyers do not have to take your word for it. Both matter enormously — for expensive cards, where the authentication and the agreed condition unlock a large and liquid market of cautious buyers. For a card worth pocket change, you are buying authentication nobody needs and a condition opinion nobody will pay extra for.
The hope tax
Much grading is driven by hope: maybe this one comes back a perfect score and becomes worth a fortune. Occasionally it does. Usually it comes back a good-but-ordinary grade on an ordinary card, and the plastic cost more than the card gained. Grading on spec, in bulk, is a tax on that hope, and the grading companies are the ones who collect it.
The rule
Grade when the card is valuable enough that authentication and an agreed grade meaningfully widen its market and lift its price well past the fee — or when it is a key card you want protected and provenanced for the long term. Otherwise, sleeve it, store it well, and keep it raw. A cheap card in a slab is still a cheap card, now with a receipt for the privilege.