Does the American English hesitation sound “uh” imply ignorance, like “d’uh”?

In British English, a pause in speech is usually marked by the word “er” or “erm” and means something like “let me think”, or “what’s the word”. There is no implication of anything other than hesitation.

The same is used in American English, but most often it seems to be transliterated as “uh”. Because of the existence of “d’uh” and “d’oh”, which imply a stupid mistake or a facepalm situation, I wonder if “uh” has an added implication that the speaker is stupid or ignorant? This seems possible because an intelligent and practised speaker will often be able to construct a speech without hesitation or filler words like this.

No, uhs do not imply that the speaker is stupid or ignorant. In my experience (which includes several thousand hours transcribing natural speech) it is simply not true that “an intelligent and practised speaker will often be able to construct a speech without hesitation or filler words like this.” The most I would concede is that a practised speaker will occasionally be able to construct such a speech.

On the other hand ...

Yes, putting uhs in the written representation of someone's speech will usually imply that the speaker is stupid or ignorant. Any departure from conventional orthography is inherently marked as non-standard, even if it in fact represents the universal practise of the most articulate and highly educated speakers. Not even the most skilful classical actor says “You didn't tell us”; but if you write that Sen. Beauregard complained to the witness “Ya din tell us”, your readers will conclude that the Senator is an illiterate redneck.

In my work I have to produce transcripts very carefully and precisely, so I can identify convenient and plausible cut points. All the uhs are there. But if I have to submit transcript or a resulting script to a client (who may well be the subject interviewed) I am just as careful to take the uhs out in her copy.