I've listened to a couple of Hitler's speeches and although I don't speak German I noticed that he seems to speak in a really clipped way, almost as if he is shortening all his vowels and biting his tongue at the end of every word. I just assumed that this was Hitler being Hitler. Recently though I watched this web program on Bavarian food and noticed something similar with some of the interviewees.
As a followup question, If Hitler did speak with a Bavarian accent how pronounced was it? Did people care? For instance, might he, or a person like him, face snobbery on account of a pronounced provincial accent?
as a German speaker : no he didn't speak with a Bavarian accent (at least later in his life in public, see below). it's more like standard German with an unusually strong emphasis on pronouncing all the R's (seems to have been en vogue back then) . probably with a hint of Austrian, where he was born.
it's pretty close to written German in any case, with clear vowels (unlike Bavarian).
modern day CSU politicians speak with Bavarian ( and francish) accent often. if you want a comparison
or this https://www.youtube.com/watch?v=GqC9TE5Pfog
if you don't speak the language (well) then, it's kind of difficult to distinguish between accents. it took a lot of experience with the english language for me to more or less tell where an english speaker is from (like "the guy is scottish", "north of england", "noo yoack", "likely australian, might be new zealand though", ...).
edit:
i found some source on the web, that says:
Bei der Sprache des späteren Diktators fällt auf, dass der bayerisch-österreichische Dialekt, den Hitler bis zum Ende des 1. Weltkriegs sprach, bereits in den 20er Jahren völlig zugunsten des affektierten, keiner bestimmten deutschsprachigen Region zuzuordnenden Sprachstils gewichen ist.
which basically says, that the bavarian-austrian dialect Hitler spoke until the end of World War I, had already been fully replaced during the 1920s in favour of the contrived [not sure if that's the correct word here] style of speech not attributable to any specific german language region.
http://www.musikarchaeologie.de/hitlerprojekt.pdf (the document mentions a fellow soldier as the source for his different dialect in 1918)
more:
Balthasar Brandmayer, ein Steinmetz aus Bruckmühl bei Bad Aibling und Kriegskamerad Hitlers, der am 31. Mai 1918 bei Juvigny schwer verletzt wurde, berichtet in seinen Memoiren vom letzten Meldegang am 26. Mai 1918, Hitler habe sich in tiefstem bayerisch-österreichischen Dialekt von ihm verabschiedet. Brandmeyer traf Hitler 1922 bei einem Veteranentreffen im München wieder sowie abermals 1932 und bemerkt, dass sich Hitler äußerlich sehr verändert hätte. Der ‚plötzliche‘ Dialektwechsel irritiert insofern, als man selbst perfekt hochdeutsch sprechenden Österreichern den Dialekt der Kindheit fast immer a nhört.
Brandmayer, a fellow soldier of Hitler's, mentions in his memoirs that Hitler had a bavarian-austrian accent, when the two last met in 1918. (they later met again in 1922 and 1932.)