Форум

Что то вроде:

User-agent: *

Disallow: /bitrix/
Disallow: /search/
Allow: /search/map.php
Disallow: /club/search/
Disallow: /forum/
Disallow: /club/group/search/
Disallow: /club/forum/search/
Disallow: /communication/forum/search/
Disallow: /communication/blog/search.php
Disallow: /club/gallery/tags/
Disallow: /examples/my-components/
Disallow: /examples/download/download_private/
Disallow: /login/
Disallow: /tests/
Disallow: /auth.php
Disallow: /personal/
Disallow: /communication/forum/user/
Disallow: /e-store/paid/detail.php
Disallow: /e-store/affiliates/
Disallow: /club/$
Disallow: /club/messages/
Disallow: /club/log/
Disallow: /content/board/my/
Disallow: /content/links/my/
Disallow: /*/search/
Disallow: /*PAGE_NAME=search
Disallow: /*PAGE_NAME=user_post
Disallow: /*PAGE_NAME=detail_slide_show
Disallow: /*/slide_show/
Disallow: /*/gallery/*order=*
Disallow: /*?print=
Disallow: /*&print=
Disallow: /*register=yes
Disallow: /*forgot_password=yes
Disallow: /*change_password=yes
Disallow: /*login=yes
Disallow: /*logout=yes
Disallow: /*auth=yes
Disallow: /*action=ADD_TO_COMPARE_LIST
Disallow: /*action=DELETE_FROM_COMPARE_LIST
Disallow: /*action=ADD2BASKET
Disallow: /*action=BUY
Disallow: /*print_course=Y
Disallow: /*bitrix_*=
Disallow: /*backurl=*
Disallow: /*BACKURL=*
Disallow: /*back_url=*
Disallow: /*BACK_URL=*
Disallow: /*back_url_admin=*
Disallow: /*index.php$

User-agent: Yandex
Disallow: /cgi-bin
Host: ваш_сайт.ru

в случае использования фильтров по товарам нужно еще и их от индексации закрыть:

Disallow: /*?set_filter=

ну и описание категории выводить только на первой странице пагинации и не показывать при отфильтрованных товарах: