I am not sure about the dipping ... but if PCGS blessed it as not being cleaned or at least cleaned badly, it's good enough for me. I think PCGS is one of the best grading companies out there. Them and NGC. I was shocked a few years back when I found out that PCGS wouldn't grade coins that were cleaned (or cleaned badly), but instead would call them "Genuine" By the way, I am no expert on cleaning but I thought that dipping tends to make coins sort of flat looking (all one color)?
Well in any case, I do have that fall back 7 day return policy ... you just can't beat seeing the coin in hand! And I have returned my share of eBay purchases!!
PCGS and NGC routinely and knowingly certify and grade dipped coinage in problem-free holders everyday. This is the one surface manipulation that is accepted by nearly every coin collector in the US, even if they do not know they are buying dipped coins. The 1917 SLQ was saved in rather large numbers so it would not be unheard of for an original, completely white piece to be on the market. However, these coins are now 93 or so years old and their tendancy is to tone somewhat. Your piece looks to be devoid of even the least trace of color, which would make me think it has had a bath. Is this bad? Not necessarily. Many folks prefer this look and the hobby-industry accepts it as an acceptable manipulation. If a coin is overdipped, dipped too many times, lightly circulated or simply so dark that it is not a good candidate for dipping then you have a good chance of obtaining a flat or dull white coin. These inappropriately or incorrectly dipped coins are often rejected by PCGS and NGC for certification in problem-free holders. If the coin in question was dipped, it still appears to be completely acceptable to the vast majority of collectors and dealers.