We have a 2005 Jayco Eagle 28BHS, and LOVE it. My only complaints are that it has the short queen bed, and it's a bunkhouse TT. Kids are gone now and it would be nice to move to a 5er, with a full queen bed (I'm 6'3").
As long as it's taken well care of I wouldn't worry about it at all. Our plastic side fenders have cracks in the short areas due to normal aging etc, definitely not a blow-out. We have NO water issues around the slide (or anywhere) when driving in hard rain or sitting (slide either open or closed).
Good luck!