Tweetbot can use regular expressions to mute tweets in your timeline and mentions.

tweetbot-mute-regex.md

Hashtag abuse

Three or more hashtags.

#[^#]+#[^#]+#

Long hashtags (15+ characters): #hashtagpunchline

#[^ ]{15}

CamelCase hashtags (3+ Words): #NotSelfAware

#[^a-z ]+[^A-Z ]+[^a-z ]+[^A-Z ]+[^a-z ]+[^ ]*

Painful to read

Unforgivable word shortening: I'm near ur place r u busy?

\sur\s
\sr\s
\su\s

Mass conversations (4+ Mentions): @guy @dude @otherguy @man totally.

@[^@]+@[^@]+@[^@]+@

Retweet chains (2+ RTs): OMG RT @teengirlsquad RT @beebz I'm thinking of you.

RT[^RT]+RT

Mentions with only a URL (spam): @imathis tinyurl.com/spam

^@imathis *https?://[^ ]+$

For the 3 hashtags one, I would have said (#[^# ]+[ ]*.*){3} 😄
Yours will not catch the 3rd hashtag completely, in a tweet such as "#magic is #cool and I also like the # sign." The third # is not a hashtag, but it still is counted as one.

In recent developments, I would add:

Mute tweets longer than 140 characters: [^]{140}

See https://twitter.com/rolfje/status/929643146002255872

Apparently that does not work correctly, and .{140} means I loose all 140 char tweets with expanded links in them. I think this requires more work.