ACROSS

 1 As they say, 22 and 24 down no matter how you slice it? (1,5,2,4)

10 You might find even it a rather childish quality. (7)

11 Entering–but no farther than this? The satin sofa really shows signs of it. (7)

12 Search around a place frequently visited by a ghost down south? (5)

13 Has left on the sort that makes prints, perhaps. (4-5)

14 Supportive–but just there in case of emergency? (8,2)

18 and 16 The abbreviated state attributed to Mr. Whittington? (A large and colorless example of literary fame.) (4-4)

20 More than cold, being from the Orient! (7,3)

23 Evidently things like pintos can be heard to show what Jack went up. (9)

25 String good fortune together, like the old composer. (5)

26 Part of a regular clam picnic–though some make light of it. (3,4)

27 I get such a long way behind time, put in quarantine! (7)

28 The first ingredient in the traditional plot–merely bigots making such. (3,5,4)

DOWN

 2 Classically, the first flower of spring. (7)

 3 Does it go in and out smoothly–especially late in the day? (8)

 4 In Naples, the twisted trunks of them can send out a stream of water. (9)

 5 Gathered at the edge of what might be a loud-sounding river. (5)

 6 Like matching collections, these should prove valuable. (6)

 7 Chopped up fine, and also fed by someone called this in the eastern Mediterranean. (7)

 8 Port and starboard lights are usually found this way, where troubles are common. (2,3,4,4)

 9 Would a commonly talked-of monkey have them on hand? (They should be both offensive and illegal.) (5,8)

15 Not the names mentioned in a white paper, though one could get it back still. (9)

17 Monotonous intonation, though many vocalists can do it well. (8)

19 Sounds ”a little smoky" to carry a pitcher from Chicago, perhaps. (4,3)

21 A dirty song–or just what the boys in the smoke-filled room have to put up with? (4,3)

22 and 24 Just a simple custard implied, by comparison? (2,4,2,3)