Is buwsuckz.com confusingly similar to Buw?

Yes according to this decision D2006-0462 (WIPO), which only states that "The Complainants’ trademark “buw” is obviously confusingly similar to the domain name buwsuckz.com", and further adds that the fact that

the domain name incorporates the mark “buw” with the addition of the derogatory word “suckz” does not warrant a finding to the effect that the domain name in question would not be considered as confusingly similar within the meaning of the meaning of Paragraph 4(a)(i) of the Policy (see cases cited by the Complainants and listed thereabove).
WIPO Overview of WIPO Panel Views on Selected UDRP Questions majority view states that "a domain name consisting of a trademark and a negative term is confusingly similar to the complainant’s mark. Confusing similarity has been found because the domain name contains a trademark and a dictionary word; or because the disputed domain name is highly similar to the trademark; or because the domain name may not be recognized as negative; or because the domain name may be viewed by non-fluent English language speakers, who may not recognize the negative connotations of the word that is attached to the trademark.
Relevant decisions: Wal-Mart Stores, Inc. v. Richard McAllen d/b/a For Sale, WIPO Case No. D2000-0662 , Transfer; A & F Trademark, Inc. and Abercrombie & Fitch Stores, Inc. v. Justin Jorgensen, WIPO Case No. D2001-0900 , Transfer; Berlitz Investment Corp. v. Stefan Tinculescu, WIPO Case No. D2003-0465 , Transfer; Wachovia Corporation v. Alton Flanders, WIPO Case No. D2003-0596 among others, Transfer".
This Panel agrees with the reasoning therein.