Measure words for disrespect
General answer to disrespectful measure words
I can't recall any special disrespectful measure words in Chinese. Such disrespectful phrases are just expressed with simple measure words according to the noun. Like

他是

一个笨蛋 [offensive level: 1]

一个饭桶 [offensive level: 2]

一个贱人 [offensive level: 4]

一个傻逼 [offensive level: 5, with profanity word 屄/逼(cunt)]

一个二逼 [offensive level: 5, with profanity word 屄/逼(cunt)]



or


一坨屎 [offensive level: 3]

一只(个)禽兽 [offensive level: 2]

一条走狗 [offensive level: 2]



Note that the offensive level is my personal feeling: 1 is the lowest and 5 is the highest. You'd better not use offensive level &gt;= 3 words when speaking to somebody face to face, or, you'd better be ready for a fight :)
Metaphor of measure words
A few Chinese people use measure words 只/坨 to show emphatic disrespect with metaphor.

他是一只小人。 (the measure word implies he is even not a human.)

But it is rarely heard in daily life. Interestingly, the official editorial often use

一 小撮 不明真相的群众
一 小撮 犯罪分子

to describe some kind of people are really few with a derogatory sense. It's a metaphor too, implying that kind of people are just like a small pinch of dust.
Common ways to emphasize your expression
To emphasize the expression, you can omit the numeral

他是个饭桶。 He is a scalawag.

Or you can also use 就是, 真是

他就是个饭桶。 He is exactly a scalawag.
他真是个饭桶。 He is really a scalawag.

And for shouting, omit the verb 是

他个饭桶。
你个傻逼。