A general note about IOSYS themselves: While they are undoubtedly one of the most popular remix groups, there are those who [[DarthWiki/RuinedForever hate what they do to the original songs]], find their videos annoying, and consider them to be sell-outs for doing things like taking on commercial jobs and selling their [=CDs=] through Amazon. If you can get past that, some of IOSYS's more bubblegummy songs are hit-or-miss, and your feelings about the [[AudioAdaptation drama tracks]] will vary depending on your understanding of Japanese, how well you tolerate the characters' voices, and so on.

* SugarWiki/AwesomeMusic: Many of their hits [[AwesomeMusic/{{Touhou}} are very, very liked]].
* EarWorm: Like you wouldn't ''believe''!
* MisattributedSong: Because of their status as the best-known ''Touhou'' remix group, expect the work of other ''Touhou'' remixers such as Silver Forest and Cool&Create to be misattributed to them, especially by the Western fandom.
** On the flip side, because IOSYS does work with arrangers, lyricists, and vocalists from other circles and songs that they've worked on sometimes appear on other circles' [=CDs=], there is occasionally a point of contention as to which circle the song should be considered belonging to (for example, [[http://www.youtube.com/watch?v=X-N6YxVgjok "Mizuhashi Jealoussic Park"]], which originally appeared on [=ALiCE'S EMOTiON=]'s ''Chaos Flare'' album and later on IOSYS's ''Touhou Ageha'').
* TastesLikeDiabetes: Some of the videos tend to fall under this. Just ''try'' to watch "[[http://www.youtube.com/watch?v=hXkqJxYdbdg You Should Drink Cucumber-Flavored Beer!]]" without having your teeth rot out.
* {{Tearjerker}}: The ending of "Alice -> Sweet" certainly qualifies. The MayflyDecemberRomance fanvid really caps it.
** "Artificial Children", another Alice song, becomes quite sad when you realize it's about Alice wondering if her dolls have life or not.