Conversion Audit Finds 60% Fake Conversions – Home Services Company Saves £8,400/Month

The Situation: Great Numbers, Bad Reality

A home services company (plumbing and heating) was running Google Ads across Search and Local campaigns. Their agency was reporting excellent results: 180 conversions per month at £34 CPL.

The business owner had a nagging problem: the phone wasn't ringing like the dashboard suggested. He booked a conversion audit.

What the Audit Found

Issue 1: Phone Click Counted as Conversion + Call Conversion = Double Count

Every mobile click on the phone number was firing TWO conversion tags:

• The Google Ads auto-collected "click-to-call" event
• A custom GTM trigger on the phone number click

Every call was being counted twice. This alone inflated conversions by ~40%.

Issue 2: Form Submit Tag Firing on Page Load

The "Quote Request" conversion tag was attached to a GTM trigger that fired on the thank-you page URL — but that URL was also being indexed by Google's bot crawler. Every Google bot visit to the thank-you page (for quality score purposes) was registering as a conversion.

Analysis of the conversion timestamps showed 22% of conversions were firing between midnight and 4am — the bot traffic window.

Issue 3: No Bot Traffic Filtering

Google Tag Manager's client-side container doesn't filter bot traffic. The conversion tag fired for any request that loaded the page — human or automated. Without server-side filtering, the tag had no way to distinguish a real visitor from a crawler.

The Real Numbers

After removing duplicates and bot-triggered conversions, the actual monthly conversion count was 72 (not 180). Real CPL: £86 (not £34).

The campaigns were burning £8,400/month on a false signal. Smart Bidding was optimising for bot traffic patterns — not real customers.

The Fix

Phase 1: Clean Up Existing Tags (Week 1–2)

• Removed duplicate phone click conversion — kept only the call duration conversion (calls > 60 seconds)
• Changed thank-you page trigger to fire only after DataLayer push from form submit event (not page load)
• Set conversion counting to "One per click" with 7-day lookback window

Phase 2: Server-side GTM Deployment (Week 3–5)

We deployed a server-side GTM container on Google Cloud Run to handle all conversion processing:

• All conversion events routed through sGTM server
• Bot user agents filtered server-side using request header inspection
• IP exclusion list for known crawler ranges
• Event deduplication via transaction_id parameter

With server-side processing, conversion events are validated before being sent to Google Ads — eliminating the entire category of bot-triggered conversions.

Phase 3: Conversion Validation Logic

Added a server-side rule: conversions only pass through if:

1. Session duration > 5 seconds
2. User agent not in known bot list
3. IP not in crawler/datacenter range
4. Form event has valid form_id parameter

Results at Week 8

With clean data, Smart Bidding retrained within 4 weeks. The campaigns started bidding on the right signals — real homeowners looking for plumbing services, not bot traffic patterns — and CPL dropped from £86 to £28.

Monthly savings: £8,400 per month in wasted budget that was previously funding bot-optimised campaigns.

What to Watch for in Your Account

These issues are more common than most agencies admit:

1. Phone click + call conversion duplication — check your conversion actions for any event counted on both mobile click and call completion
2. Thank-you page as trigger — always use DataLayer pushes, not URL-based triggers, for form conversions
3. Missing bot filtering — if you're not on server-side GTM, you have no protection against crawler conversions

Related Services

• Conversion Tracking Setup & Audit
• Server-side GTM Setup
• Google Ads Management