Hard not to appreciate Clement of Alexandria, here commenting on the holy kiss (Rom 16:16; cf. 1 Cor 16:20; 2 Cor 13:12; 1 Thess 5:26; 1 Pet 5:14):

Love is not proved by a kiss, but by kindly feeling. But there are those who do nothing but make the churches resound with a kiss, not having love itself within. For this very thing, the shameless use of a kiss (which should be mystical), causes foul suspicions and evil rumors. The apostle calls the kiss holy. When the kingdom is worthily tested, we express the affection of the soul with a chaste and closed mouth, by which chiefly gentle manners are expressed. (The Instructor 12 [ANF 2:291].)

Michael Riley raises some good questions on the holy kiss here.

I still remember hearing a sermon Chuck Bumgardner once preached on the holy kiss that’s worth listening to. 

The church of my relatively recent ancestors attended practiced the holy kiss (as a boy, we as a family still attended there). Men exchanged it with men, and women with women. Some were bold enough to plant the sign on the lips of others, and others did the side swipe.