Are federal travelers and diners cheapskates when it comes time to plunk down a tip? Is the Reagan administration the most successful ever when it comes to selling the media "bad" stories about civil servants? Does budget cutter Donald Devine still favor trimming the federal work force now that he is out of work?

Those are the subjects of letters in today's Monday Morning Quarterback.

First, from a motel-restaurant employe:

"Your Monday Morning Quarterback letter-writers bemoan the public's hostility toward them. As a restaurant-motel employe, I can give you one reason: Civil servants and military officers are cheap!

"Lots of civil servants and military personnel visit here. Motel employes clean their rooms, and drive them to the airport and the Pentagon, subway stations, etc. For our efforts we get a 'thank you' and very few tips.

"One would think there is a government regulation prohibiting tipping. So, I don't shed any tears for tightwads griping about their cost-of-living raises and pensions." Sign Me: Irked

" . . . The manipulation of the media, a major goal of the current administration, the most successful in my 20 years experience, has contributed mightily to the anti-civil service climate.

"Building on a perception of civil servants as overpaid and underworked, the administration has promoted an image of federal employes as defaulters on government loans.

"Education loan delinquency came first. Federal employes were computer matched against the delinquency list and the numbers were broadly publicized. A close look at the numbers, though, shows that less than 1 percent of the delinquent loans were to current or former federal employes. This is not an apology or excuse . . . but I do wonder who the other 99 percent are. And I haven't seen much publicity on what was being done to see that they pay up.

"Then, The Post reported March 18 on Housing and Urban Development's efforts to track down delinquent home improvement and similar loan recipients employed by the government. Again, big numbers. But in that article the facts were not fully presented. No mention of the total number of delinquencies, but I doubt if feds represent the bulk of the delinquencies.

"Is this administration practicing the good management it preaches by focusing so many resources on a miniscule portion of their total delinquency portfolio? Or is it their intent to promote a negative image of public service employes?" V.F., Arlington

"Even though one may empathize with another's misfortune, there is also poetic justice in Donald Devine former director of the Office of Personnel Management losing his job. Probably no one showed as much enthusiasm for reducing the government work force as he did. Now that he and some of his aides have been removed from the federal work force, one can't help wondering if he is consistent and views it as a positive 'saving' of government funds?" J.T., Rockville