The ornamental design for a grillbrushattachmenthavingspiral bristles and auxiliary scraper, as shown and described.
FIG. 1 is a rear isometric view of a grill brush attachment having spiral bristles and auxiliary scraper in accordance with the new design;
FIG. 2 is a rear view thereof;
FIG. 3 is a top view thereof;
FIG. 4 is a front view thereof;
FIG. 5 is a bottom view thereof; and,
FIG. 6 is a side view thereof.
The broken lines shown on both sides and the bottom of the grill brush attachment represent the bounds of the claim and all of the other broken lines are understood to illustrate the environment in which the article embodying the design is used. None of the broken lines form part of the claimed design.