The website http://truecovenanter.com/reformedpresbyterian/reformed_presbytery_testimony_against_immoralities.html#rp_testimony_against_immorality_note_01 has this insightful information regarding promiscuous dancing:
The Westminster Assembly in their Larger Catechism Quest. 139. The Reformed Church of Scotland, in their Act 19 July 1649. Session 18. Messrs. Perkins, Durham, Watson, Boston, Willison, R. Erskine, J. Brown, with many others, have all given their testimony against promiscuous dancing. Instead of quoting their sentiments on this subject at large, the following abstract of their arguments is here given.
1. Promiscuous dancing has a tendency to promote too much familiarity between the sexes, and to lead them into the way of temptation.—2. It is the favourite amusement of light and vain persons, who are lovers of pleasure more than lovers of God.—3. It exposes to such company, as has a tendency to corrupt the morals and deprave the heart.—4. It tends to the gratification of these corrupt inclinations and passions, which we are commanded to crucify and mortify.—5. It is one species of revelling, which is ranked among the damning works of the flesh, 1 Pet. 4.3.—6. It is an open violation of our baptismal vows, as it is an evident serving, instead of renouncing, of sin, Satan, and our own lusts.—7. It is a great waste of precious time, and commonly at very unseasonable hours.—8. It is offensive to the serious and godly, who have their senses exercised to discern between good and evil.—9. It is never done with a design to glorify God, as all a Christian's actions ought to be.—10. The sinfulness of it is greatly aggravated, when committed by persons trained up, and instructed in the criminality of such practices, and their becoming the defenders of it, against light and knowledge.—11. It unfits the mind for the serious exercises of religion, and is ready to make us neglect the duties of the closet, or family.—12. It puts us into a frame very unsuitable to meet with death. Numbers have been summoned before God immediately after a dancing ball, and it is to be hoped no Christian will think it a proper preparation for an eternal state.
The Free Presbyterian Church of Scotland rightly prohibits such of her communicant members.