AFTER-HOUR SPOTS AND BOTTLE CLUBS: These used to be common, but few New Yorkers now seem willing or able to imbibe after the deadline. There remain practically no too-late spots. The few that do, pose as private clubs, selling no liquor, but serving "members" out of their own lockers. (If they know you well, your locker, by coincidence, is always stocked with just your brand.) Celebs go to the Club Carr, on Fifth Avenue, at E. 69th St. Once raided, not for liquor, but for entertainment sans license, the club beat the rap. Another is the Gold Key, W. 56th near Sixth Avenue. CABARET INFO: Hostesses are not permitted in clubs. Female entertainers are forbidden to sit out with customers. Waitresses may not be employed after midnight, except in hotels. Most night clubs present the first show at 8 or 8:30, their second at 12 or 12:30 and their last at 2 or 2:30. The Latin Quarter presents two shows nightly, except on Saturday, three. Few clubs except the Stork and El Morocco have a cover charge. But most good hotel grill rooms do. All other clubs have minimum charges, from $2 to $5 on weekdays, up to $6 a person at some, Saturdays and $7.50 opening nights. Though it's not a law, the cops have advised saloon-keepers they don't like 'em to cater to unescorted ladies after 10 P.M. even if they come in groups, so you femmes sans boy friends had better get yourselves one if you want to see our night life. TIPS: If you want to get into many night clubs, or get good tables in any, you have to stake the headwaiter, the tip ranging from $2 in the more modest places up to $10 and $20 at the Stork and El Morocco. Waiters, too, expect more here than in other cities. A 10 per cent tip will earn you an icy stare most anywhere. The average night club habitué usually adds on about 25 per cent, but more often figures the tip on the length of time he occupied the table and the amount of service he received. In other words, if his check was only $2, but he sat at the table so long the waiter lost two or three other parties, he'd reward him accordingly. WAITERS' RACKETS: Padded checks and switched checks are common. In the first instance, the waiter makes a "mistake" in the addition, in his favor, then, after you pay, he erases the wrong total and turns in the correct amount. On the switch racket, he presents you with a larger check written for another table. Most people don't study the items. But if you do, he apologizes and says he gave you the wrong check. If you pay, he turns in your smaller right check, pockets the difference, then uses the large check over again. CHECK YOUR HAT: Your "voluntary" contribution to the hat-room gal isn't as voluntary as you imagine. The concessionaire's license from the city permits him to exact a flat charge for each item checked, if he desires.