If you live in Guelph, you’ve probably seen the flyers: “Whole-house duct cleaning—$99! Limited time!” Or you’ve answered a call from someone “in your neighbourhood” offering a same-day special. Some offers are fine; many aren’t. In a city with century homes near Exhibition Park and tight-envelope builds in Clairfields, a rushed, under-equipped crew can do more harm than good—stirring dust into rooms, damaging liners, or upselling services you don’t need. Here’s a no-nonsense guide to help you spot the scams and book a team that actually improves your air.

1) The Too-Good-to-Be-True Price

Red flag: “Entire house for $99–$149, any size.”
Real duct cleaning takes time, power, and two trained techs. In most Guelph detached homes, a thorough job runs 2–4 hours with proper negative-air machines and branch agitation. Rock-bottom pricing usually means one of two things: a blitz-and-bolt that only vacuums a handful of registers, or a bait price followed by aggressive upsells at the door. Ask for an itemised, all-in quote that lists supplies, returns, trunk lines, furnace cabinet, and optional add-ons (dryer vent, AC coil face clean, sanitizer only if warranted). If they dodge specifics, pass.

2) No Written Process (Just Vague Promises)

Red flag: “We blow compressed air through the vents” and that’s the whole explanation.
Effective cleaning is source removal. A credible provider explains the steps in plain language:

• Connect a high-CFM negative-air machine at the trunks to pull debris out of the system.
• Mechanically agitate every branch (rotary brush or air whip) to dislodge compacted dust.
• Clean return and supply trunks, furnace cabinet, and blower compartment.
• Use HEPA containment so loosened debris doesn’t cloud your living room.
• Seal service openings with code-compliant plates.
  If a company can’t describe where they connect, which branches are hardest in your layout, or how they’ll protect lined duct, you’re not buying craftsmanship—you’re buying noise.

3) No Photos, No Proof

Red flag: “You’ll smell the freshness.”
Scent is not evidence. Before/after photos (same angle, labelled) of your returns, supplies, trunks, and the furnace cabinet are standard in 2025. A good crew can also show short clips when a run is heavily clogged or damaged. If they won’t document the work, expect a superficial pass you can’t verify.

Tip: Ask for a one-page post-service summary: what they found (e.g., return leak near the basement), what they fixed, and what needs follow-up.

4) The Hard Sell on Chemicals

Red flag: “Hospital-grade sanitizer included with every clean.”
Sanitizers have a place—post-renovation, odour issues, pests, or documented microbial growth—but they’re not routine. Scammers lean on mystery mists and fragrance bombs to create the illusion of clean. If a product is recommended, you should hear the name, dwell time, ventilation steps, and see an MSDS. Otherwise, you’re paying for perfume.

5) Uninsured, Unidentifiable, or Cash-Only Crews

Red flag: No company name on the truck, techs without ID, pressure to pay cash for a “better rate.”
Legitimate contractors carry commercial liability, are listed with a local address, and can show WSIB coverage for Ontario. Ask for documentation—politely but firmly. In older Guelph homes with fragile plaster and narrow stairways, insurance and training matter. If they balk, you’ve got your answer.

6) One-Hour Whole-House “Miracles”

Red flag: “We’ll be in and out in 60 minutes.”
Time depends on home size and system complexity, but a solid rule of thumb for typical Guelph detached homes is 2–4 hours with two techs. Century homes near Exhibition Park may take longer (hidden spurs, lined trunks); newer Clairfields builds with flex runs require care to avoid damage. One hour? That’s a drive-by.

7) Per-Vent Ambush and Doorway Price Hikes

Red flag: A low base price that explodes after counting vents, “discovering” extra trunks, or claiming the furnace cabinet isn’t included.
Stop this early by asking for a written, itemised scope that lists: number of supply registers, number of returns, inclusion of both trunks, the furnace cabinet/blower, and the per-vent price for any legitimate extras. Have them confirm HST, any travel or parking fees (condos), and a realistic time estimate. If the dispatcher won’t email it, expect a bait-and-switch.

8) No House Protection Plan

Red flag: “We’re careful,” with no specifics.
Professional crews protect your space: boot covers, drop sheets, corner guards on tight stair turns (think Old University houses), screws collected in a container, and a vacuum pass where they worked. Doors aren’t left open in February; pets aren’t stressed by slamming. If this sounds fussy, good—that’s the point. Sloppy containment blows dust through your home and costs you time to re-clean.

9) Pressure Tactics and Limited-Time Panic

Red flag: “We’re on your street right now—book in the next 15 minutes.”
Urgency is a sales tactic, not a service standard. A reputable company can hold a price for a reasonable window and encourages you to check recent local reviews (Kortright Hills, Grange Hill East, Downtown). If the rep gets defensive when you ask for references or photos, end the call.

10) Reviews That Sound… Off

Red flag: Dozens of generic five-star reviews on the same day, light on detail, heavy on adjectives.
Read reviews like a buyer:

• Sort by Newest.
• Look for specifics: punctuality, cleanliness, technician names, time on site, and photo proof.
• Pay attention to homes similar to yours (century vs. new build).
  Repeated complaints about surprise fees or “in and out in under an hour” are a pattern—believe them.

What a Legitimate Visit Looks Like (Quick Reference)

1. Pre-arrival: Written quote with full scope, ETA text, named techs.
2. Walkthrough: System mapping, protection set-up, access explained.
3. Method: Negative air at trunks, mechanical agitation at each branch, trunks + furnace cabinet cleaned, HEPA containment.
4. Proof: Same-angle before/after photos; notes on issues (filter fit, return leaks, humidifier pad).
5. Wrap-up: Clean work areas, simple maintenance tips, clear invoice—no surprise add-ons.

How to Protect Yourself in 3 Steps

1. Get it in writing. Itemised scope, price, add-ons, time estimate, and taxes.
2. Ask for proof. Insurance/WSIB, process description, and photo documentation.
3. Choose timing wisely. Early spring, post-pollen (late May/June), or pre-heat (Sept/Oct) stretch results and reduce the temptation to accept a “right-now” street special.

Bottom Line

In Guelph, the difference between a scam and a solid duct cleaning isn’t the logo on a truck—it’s method, documentation, and respect for your home. If a company explains the process clearly, proves results with photos, protects your space, and prices transparently, you’ll hear smoother airflow, see less dust, and breathe easier. If they won’t answer basic questions, don’t debate—just don’t book.