Here’s a list of red flags
1. DJ’s who Can’t beatmatch
2. DJ’s who use only Spotify
3. DJ’s who burn tracks from YouTube other services (these tracks are low quality and will hurt your ears!)
4. DJ’s who don’t have midi controllers (decks), or CDJ’s
5. DJ’s who use tracks with a quality of less than 192kbps
6. DJ’s who “fade mix” - this is a fancy Spotify playlist. Sure, for the singalongs, fade mixing is appropriate, but this should be limited.
Even if you hire a DJ, it is their responsibility to be professional and achieve certain standards If you are paying a premium.