€257 into Reddit Ads for my niche SaaS: 31 signups, 1 activated user, 0 paying. Every trap I'd tell a first-time Reddit advertiser to dodge.

1. "All devices" doesn't mean "desktop + mobile." It means mobile.
   Campaign 1 ran desktop-only and converted 2.67% of clicks to signups. For campaign 2 I "fixed" the targeting to all devices, expecting mobile on top of desktop. The auction had other plans: 95.4% of clicks came from mobile, because that's where Reddit's cheap inventory lives. Desktop didn't get added to — it got replaced. Campaign 2: 0 signups from 474 clicks. If the old rate had held, the odds of that being luck are about 1 in 370,000. It wasn't luck; it was a completely different traffic buy wearing the same campaign name. If you need desktop traffic, you must force it with device targeting — the auction will never volunteer it.

2. The Traffic objective buys clickers, not customers.
   Same campaign 2 mistake, compounding the first: I also switched from the Conversions objective to Traffic. Cheaper CPCs (€0.14, down 30%)! Which flattered ads that were performing worse than the ones they replaced. Traffic optimization finds people who click things. That is genuinely all it finds.

3. Cheap clicks have a geography, and it isn't where your customers are.
   When I finally audited who was signing up: 0 of 30 signups from institutional (.edu) emails, top countries India/Pakistan/Vietnam, median time from landing to signup: 53 seconds. Nobody evaluates a SaaS in 53 seconds — that's a drive-by. My audience is literally "people with university email addresses" and I'd bought none of them. Campaign 4 runs a hard geo allowlist. Watch your geo report on day 1, not day 7.

4. Pre-register your kill thresholds.
   Before campaign 2 I wrote down: kill any creative under 0.4% CTR after 50k impressions. One concept hit 49,338 impressions at 0.322% — killed, no agonizing, no sunk-cost debate with myself. Deciding the rule before you're emotionally invested in a creative is the only reason it worked.

5. Reddit's targeting defaults will quietly widen your audience.
   My latest campaign lost its first two days to automated targeting expansion I hadn't meant to enable. Caught it, cut back to hand-picked communities only. Check every expansion toggle at launch, then check the delivery breakdown the next morning anyway.

6. Judge on your first ~10 signups' behavior, not on click stats.
   My current decision rule: if 3 of the first 10 verified-academic signups create a real publication entry, acquisition was the bottleneck. If academics arrive and still do nothing, the product is. Click-through rates can't answer that question at any sample size.

The honest ending: the cleaned-up campaign (right geos, communities-only, desktop, conversions objective — plus a rebuilt onboarding) started its first clean day this week. I don't know yet if it works. If there's interest I'll post the follow-up either way — including if it's another zero.

Anyone else advertising to an audience that blocks trackers? How do you handle attribution when 60%+ of your visitors are invisible?

Cheers :)