ボロクソな	1972	3.5%
ボロクソに	52966	94.6%
ボロクソの	1076	1.9%


ボロクソに言われる	2494	55.5%
ボロクソ言われる	2003	44.5%


ボロクソ言って	4123	43.9%
ボロクソに言って	5265	56.1%

Usage is mostly adv as に. Not sure how this entry should be dealt with really but [adj-na,n] is maybe an OK compromise until somebody else can come up with something better.

Answering my own question: I think it's OK.
Sense [1]: ボロクソな評判 - bad reputation
Sense [2]: ボロクソな扱い - demeaning treatment
           ボロクソな侮辱 - disparaging insult

Is sense [2] really adj-na? I see a lot of adverbial examples in
the refs, and I assume that's what this sense is referring to.

Google N-gram Corpus Counts
| ボロ糞　 |  1,549 |  1.2% |
| ぼろ糞　 |  2,478 |  1.9% |
| 襤褸糞　 |     73 |  0.1% | <- in daijr/s, koj, nikk, mk, gg5
| ぼろくそ | 26,967 | 20.7% |
| ボロクソ | 97,151 | 74.5% |
| ボロくそ |  1,983 |  1.5% |
| ぼろクソ |    137 |  0.1% |

Not marking 糞 as [rK] since it's in >3% of usages

@@ -8,0 +9 @@
+<ke_inf>&rK;</ke_inf>

nikk: ”価値のないもの。劣悪なもの。転じて、ひどく劣っているものとしてののしってい
うさま。ひどく悪くいうさま。ぼろかす。くそみそ。”
daijs: "ひどく劣っていること。まったく価値のないこと。また、そのようなものとしての
のしるさま。「―にけなす」"

@@ -18,0 +18,1 @@
+<pos>&adj-na;</pos>
@@ -19,0 +20,5 @@
+<misc>&uk;</misc>
+<gloss>worthless</gloss>
+<gloss>shit</gloss>
+</sense>
+<sense>
@@ -20,0 +26,1 @@
+<pos>&n;</pos>
@@ -21,1 +28,2 @@
-<gloss>trashy reputation</gloss>
+<gloss>disparaging</gloss>
+<gloss>demeaning</gloss>