Dancers want to hear the beat

Most dance forms are easier to dance when the beat is heard clearly, usually played by the rhythm instruments (drums/percussion, guitar, piano, techno rhythm tracks, etc.).

On a rhythmic intensity scale of 0 to 10, most dance music wants to be in the 4 to 10 range, depending on the type of dance.  Concert music for listening can have a quiet rhythm accompaniment or none at all, but the rhythm of most dance music should range from a gentle but clearly audible rhythm (4) to a strong driving rhythm (10).  Even quieter dance forms like rumba and club two step should have a clearly audible beat.  With only a few exceptions, avoid the quietest scale of 0 (no rhythm instruments at all, only melody) to 3 (still not clear enough to hear in a room full of dancers who might be shuffling and talking).

Shuffling and talking?  Yes, dance parties are usually noisy.  One of the common mistakes DJs make is to listen to a tune in a quiet room and think that the quiet rhythm accompaniment will be heard at a dance.  Then they find that the rhythm is lost in ambient noise of a dance party.  So if you're test-listening to music in a quiet room, aim for one or two notches stronger rhythm than you think will be needed.

When I hear dancers complain about a DJ, the most common complaint is, "I couldn't hear the beat."  The second most common complaint is about tempos...