Depending on where the recommendation is being displayed it will typically a have a "fix this recommendation" button right under the item. Then you can select t

Depending on where the recommendation is being displayed it will typically a have a "fix this recommendation" button right under the item. Then you can select that you are't interested, already own it, bought it as a gift, or simply mark it to not be used for recommendations. The problem with this is, it seems to take ten or fifteen minutes of effort to get the system to go back to showing somewhat relevant items after purchasing a few gifts, or browsing some atypical items. Who wants to spend that kind of time pruning advertisements. It's easier to just ignore them.