This is an indirect answer.
The "hosting rule" was established in 1958:
Ok, here we go now: the winning country will be hosting the next ESC
from now on!
(Generally speaking, anyway – some countries did make
exceptions once in a while)
[Source: Official Eurovision Song Contest website from 2006 (via the Wayback Machine)]
The mentioned exceptions are: (quotes taken from the official ESC website 2012)
1960: The capital of the United Kingdom, London, provided the settings for the fifth Eurovision Song Contest. This was despite
the fact that the Netherlands actually won the Eurovision Song Contest
the year before [..] the Dutch broadcaster didn't want to host the
1963: The honour of hosting this year's song contest was handed over by the French to the United Kingdom.
1972: Despite the victory of Monaco the previous year, the 1972 ESC took place in Edinburgh. The reason that the contest did
not take place in Monaco was because the small Mediterranean nation
could not provide a decent venue. However, it was later rumoured that
the real reason was that Monaco was not in a financial position to
host the contest.
1974: For the second year in three, the United Kingdom and its national broadcaster BBC held the Eurovision Song Contest
without having won in the preceding year. Due to the fact that the
Luxembourg broadcaster RTL did not wish to host the song contest again
because of financial reasons, British BBC embraced the possibility
1980: Israeli TV didn't want to host the 1980 Song Contest again even if they won it the year before on home ground.
After a lot of discussions with several European broadcasters it was
decided that the contest would be arranged by Dutch TV NOS in The
In 1976 Sweden
withdrew from the contest as Swedish TV thought that the contest had
become too commercial. They were also afraid of winning again and
having to host the expensive show again.
This led to
a new rule being introduced which meant each participant had to
contribute in part to the costs of staging the event.
the easiest way to "avoid winning" is obviously not to register for the contest in the first place (e.g. this year Poland decided not to participate)
there are precedents of countries declining hosting duties due to financial strain
Due to these two points it seems to be an unnecessary measure to deliberately send artists who cannot win.