[Runscott]

You really have to be careful with stamps. A lot of uneducated collectors date photos based entirely on stamps, even though the photo might actually be much older (obviously, it can't be newer). I just had an ebayer go after me full-frontal (with atrocious text-speak) over my dating a photo based on an attached caption. He was certain that the date-stamp he found in Henry's book overrode any other facts related to the photo. I tried to educate him, but he was a photo-Creationist and was not going to deviate from 'the word'.

• If a photo has no notes, stamps, attached news-photos or typed attachments, then you have to just use your brain. That's a hard thing to hear, but our brains supposedly only operate at 7% capacity, so you've got another 93% left for common sense.
• If a photo has a stamp AND a typed attachment, then again, you must use your brain, but your decision can be more educated. For instance, if the caption says "way back in 1920 when this photo was taken...", that's much worse news than if it has a 1920 date and speaks in present tense: "action fro yesterday's game at Fenway Park."
• If a photo has ONLY a stamp, then unfortunately you might be stuck with dating the photo based on that bit of information. You might be sure that it's 1920's, but the stamp is 1950's, but without anything else, you aren't going to convince most collectors. If I'm certain a photo is older than it's stamp, and all I have is a stamp, I'd almost rather the back was blank.