For people who have opened booster boxes in poor condition (large dents, perforated seals, etc.) - have you noticed if this makes any impact on the condition of the cards within the box?
In extreme cases yes. Just about every time it happened to impact the cards inside for me it was very apparent it was going to impact the cards inside though just from looking at the box. I have opened some really ugly boxes in my quest to open 1 of each box while trying to do it as cheaply as possible. A few times I have seen a corner that is crushed in quite badly and then had a few creased edge cards in the pack or two nearest that corner. You’ll likely be able to tell once you open the seal of the box, which specific packs will be affected. It has always been limited to only a small portion of the cards though. Many times I have opened boxes that are in just general poor condition all around and the cards inside had no issues. From my experiences it takes a fairly severe damage to the box to hurt the inner cards as they are packed fairly tight in there and are quite rugged. One specific time I recall about a third of a XY era box was looking like it had been dropped from a plane landing flat on the right side. This affected almost that entire half the box save for maybe a few middle cards in each pack. It is nice how they put the UR’s towards the middles and not on the ends.
Knowing this I have consistently tried to get good deals on some really ugly boxes and succeeded in a few cases. Many times though the owner isn’t really giving any discount sufficient to cover the risk of ~10-20% or more of the cards being creased/bent.