Putty + line drawing = weirdness

Question

Connecting to any debian installation via PuTTY results in a very strange situation: I can have correct display of line drawing, but not for all programs.

In particular Midnight Commander and aptitude seem to belong to opposite camps: If one works the other does not.

Currently I have linux set to use utf8 (LANG=en_US.UTF-8) and PuTTY likewise (Window->Translation->{Remote character set: UTF8; Use Unicode line drawing}); in this situation mc works as expected and aptitude displays "lqqqk".
if I reverse settings in PuTTY (wihout changing anything in linux) (Window->Translation->{Remote character set: ISO-8859-15; Use Unicode line drawing}); this time aptitude shows as it should and mc displays "ââ€â"; using other "Handling of line drawing characters" breaks mc and aptitude.

Other programs (e.g.: kernel menuconfig) seem to follow aptitude behavior.

What's going on "under the hood"?
How do I fix this (if at all possible)?

UPDATE: I have been living with this problem (and NO solution to be found, I am aware of many other answers, but they so address only one half of the problem: mc). As stated above I am able to make mc work correctly and I thought I was able to make aptitude/kconfig work correctly... only I need two different settings for them.

To recap:

• I have a plain, default debian server (no GUI) install (currently jessie, but this holds true for all releases)`.

• Locale is pretty standard:

  $ locale
  LANG=en_US.UTF-8
  LANGUAGE=en_US:en
  LC_CTYPE="en_US.UTF-8"
  LC_NUMERIC="en_US.UTF-8"
  LC_TIME="en_US.UTF-8"
  LC_COLLATE="en_US.UTF-8"
  LC_MONETARY="en_US.UTF-8"
  LC_MESSAGES="en_US.UTF-8"
  LC_PAPER="en_US.UTF-8"
  LC_NAME="en_US.UTF-8"
  LC_ADDRESS="en_US.UTF-8"
  LC_TELEPHONE="en_US.UTF-8"
  LC_MEASUREMENT="en_US.UTF-8"
  LC_IDENTIFICATION="en_US.UTF-8"
  LC_ALL=
  

  • I am using either the standard "xterm" setting or "putty" in Connection->Data->{Terminal-type string}; it makes no difference.
  • Certain programs work, others not; if I fix the "not working" ones I contextually break the "working" ones.
  • The "fix" consists in switching PuTTY Window->Translation->{Remote character set} from "UTF8" to "ISO-8859-15" and vice versa.
  • Extreme case is aptitude which, I discovered, can't be fixed because it seems to use two different standards: if menu and scrollbar are displayed right then pop-ups are wrong, and vice-versa.
  • Kernel configuration (make menuconfig) shows the same (wrong) behavior as aptitude.
  • I include screenshots to explicate better (nothing is changed server-side).

This was taken from KiTTY with UTF8 setting; note scrollbar is displaying correctly (and also menu (F10) display ok, I did not feel like adding other images, but I can provide, if needed).

This was taken from KiTTY with ISO-8859-15 setting; note scrollbar is "wrong", but pop-up is correct (in this case also menu are garbled). Notice also the "kind" of mis-translation is different.

Please Note: the question is not (and never was) "How to make mc display line-drawing chars", but "How to have mc and aptitude/kconfig working in the same environment".