YouTube provides features for users to indicate disinterest when presented with unwanted recommendations, such as the ``Not interested'' and ``Don\'t recommend channel'' buttons. These buttons are purported to allow the user to correct ``mistakes'' made by the recommendation system. Yet, relatively little is known about the empirical efficacy of these buttons. Neither is much known about users' awareness of and confidence in them. To address these gaps, we simulated YouTube users with sock puppet agents. Each agent first executed a ``stain phase'', where it watched many videos of one assigned topic; then it executed a ``scrub phase'', where it tried to remove recommendations of the assigned topic. Each agent repeatedly applied a single scrubbing strategy, which included disliking previously-watched videos or deleting them from watch history, as well as clicking the ``not interested'' or ``don\'t recommend channel'' button on newly-recommended videos. Overall, we found that the stain phase significantly increased the fraction of the recommended videos on the user\'s homepage dedicated to the assigned topic. For the scrub phase, using the ``Not interested'' button worked best, significantly reducing such recommendations in all topics tested, on average removing 88\% of them. Neither the stain phase nor the scrub phase, however, had much effect on videopage recommendations (those given to users while they watch a video). We also ran a survey ($N$ =300) asking adult YouTube users in the US whether they were aware of and used these buttons before, as well as how effective they found these buttons to be. We found that 44\% of participants were not aware that the ``Not interested'' button existed. However, those who were aware of this button often used it to remove unwanted recommendations (82.8\%) and found it to be modestly effective (3.42 out of 5).

翻译：YouTube为用户提供了在收到不想要的推荐时表示不感兴趣的选项，例如“不感兴趣”和“不推荐该频道”按钮。这些按钮旨在让用户纠正推荐系统的“错误”。然而，关于这些按钮的实际效果、用户的知晓程度及其对它们的信心，目前仍知之甚少。为弥补这些不足，我们通过傀儡代理模拟了YouTube用户。每个代理首先执行“污染阶段”，即观看大量指定主题的视频；然后执行“清洗阶段”，即尝试移除该主题的推荐。每个代理反复使用单一清洗策略，包括对之前观看的视频点“不喜欢”或将其从观看历史中删除，以及在新推荐的视频上点击“不感兴趣”或“不推荐该频道”按钮。总体而言，我们发现污染阶段显著增加了用户主页上推荐视频中指定主题的比例。在清洗阶段，使用“不感兴趣”按钮效果最佳，能显著减少所有测试主题中的此类推荐，平均移除88%的推荐。然而，无论是污染阶段还是清洗阶段，对视频页面推荐（即用户观看视频时收到的推荐）影响甚微。我们还进行了一项调查（样本量N=300），询问美国成年YouTube用户是否了解并曾使用这些按钮，以及他们认为这些按钮的有效性如何。我们发现，44%的参与者不知道“不感兴趣”按钮的存在。不过，知晓该按钮的用户中，82.8%经常使用它来移除不想要的推荐，并认为其效果中等（3.42分，满分5分）。