Apparently the related images button is now broken. Not sure when exactly it happened, but it has to have been fairly recent. Pressing the button just redirects you to the home page now.
feet, being an anatomy tag, is innocuous overall and filtering it will catch a significant amount of artwork (for example, anything with a fullbody of oc:anon). foot fetish, which is as bad as you imply. 
If you do not specify a field to search over, the search engine will search for posts with a body that is similar to the query's word stems. For example, posts containing the words winged humanization, wings, and spread wings would all be found by a search for wing, but sewing would not be.
| Field Selector | Type | Description | Example |
|---|---|---|---|
author | Literal | Matches the author of this post. Anonymous authors will never match this term. | author:Joey |
body | Full Text | Matches the body of this post. This is the default field. | body:test |
created_at | Date/Time Range | Matches the creation time of this post. | created_at:2015 |
id | Numeric Range | Matches the numeric surrogate key for this post. | id:1000000 |
my | Meta | my:posts matches posts you have posted if you are signed in. | my:posts |
subject | Full Text | Matches the title of the topic. | subject:time wasting thread |
topic_id | Literal | Matches the numeric surrogate key for the topic this post belongs to. | topic_id:7000 |
topic_position | Numeric Range | Matches the offset from the beginning of the topic of this post. Positions begin at 0. | topic_position:0 |
updated_at | Date/Time Range | Matches the creation or last edit time of this post. | updated_at.gte:2 weeks ago |
user_id | Literal | Matches posts with the specified user_id. Anonymous users will never match this term. | user_id:211190 |
