OK... the question...
Yes, since the First Test at Edgbaston in 2000, West Indies have been awful. Their away record barely even merits mention, their home record has got gradually worse. Last time they won more than 1 Test a series was 2002; last time they won a series was 2003; last time they won a real Test was 2005...
Nonetheless, it'd take an imbecile, frankly, to compare them to Bangladesh. As I've said a million times on this issue, it's not just about results, it's about any number of things - calibre of players playing for you for instance (to suggest a side with Brian Lara mostly in it is not Test standard is borderline ludicrous in itself, same as Zimbabwe were with Flower in there - those two, however, were not the only high-calibre players in their sides); actual competetiveness in the games another. Compare, if you will, West Indies in England in 2007 to Bangladesh in 2005. Yeah, sure, England had some better players then, but nonetheless, all the England bowlers bar Simon Jones bowled dreadfully that series. Yes, even Hoggard for the most part, who took wickets at 14 or something.
England flattened Bangladesh. Only once did a similar thing happen with West Indies. Though two of the victories were comfortable and the draw they were never in danger of defeat, nonetheless they were never walkovers. West Indies always gave the impression that they had the right to be playing the game (except at Headingley, where they were for the most part a total shambles). And the England example is merely the most obvious one: to take a more recent example. When West Indies last played Sri Lanka (without 10 or so top players missing because of the contracts row) they were whitewashed easily, but they weren't hammered by an innings with no semblence of a serious contest, not at all.
Now take the high-calibre players issue. In their entire history, Bangladesh have had perhaps 4 serious cricketers: Mohammad Rafique, Mashrafe bin Mortaza, Habibul Bashar and, in the last couple of years, Shahriar Nafees Ahmed. Plus quite a few very average ones and many, many utterly abysmal ones. Even the 4 serious cricketers they've had are, to date (Mortaza and Nafees still have plenty of career ahead of them), nothing remotely special. West Indies in the past 7 years have had Lara, Chanderpaul, Gayle, Sarwan, Wavell Hinds, Collymore, Collins. Heck, three fringe batsmen, Daren Ganga, Devon Smith and Ryan Hinds, are quite clearly far better batsmen than all but the very, very best Bangladeshis. Then who are Bangladesh's average seamers: Shahadat Hossain and I won't even go into anyone else because there hasn't even been any undue hype there. Who are West Indies'? Jerome Taylor, Fidel Edwards and Jermaine Lawson (to pick three examples). All of whom have had plenty of moments in Test cricket and are quite clearly genuine prospects, and indeed have been for years.
This is the difference between the worst-of-the-best and the best-of-the-rest.