lugubrious rhythms dredged from a river setting/blowdried vocals

[Vladv1]

As such, the arrival of Metallica, and with them this new phenomenon called ‘thrash metal’, was a watershed moment in rock history: the end of heavy metal as it had become, post-punk – either lugubrious rhythms dredged from a river setting the scene for jiggery-pokery lyrics about Satan and his followers, or self-conscious anthems full of whinnying guitars and blowdried vocals – and the beginning of a whole new thing that began by offering an alternative to the staid old ways and ended up replacing them.
Mick Wall "Enter night"
Could you please tell what the phrases in bold mean?

 

[emsr2d2]

@Vladv1 You currently have eight open threads just on the first page of Ask A Teacher. Please take a break and give other users a chance.

 

[probus]

Although @Vladv1 is currently serving a temporary ban for flooding I'd like to give him a reply to his last query. The author of the work which has inspired almost all of your recent queries @Vladv1 is evidently fond of very florid, not to say lurid English. No simile is too far-fetched, no metaphor too outlandish, no turn of phrase too extreme for that writer. Please bear that in mind when you resume posting after your ban.

 

[Skrej]

Suffice it to say that the author didn't care for the changes in heavy metal music. He found it monotonous and uninspiring from a creative standpoint.